src/sqlite3.c
author Volker Birk <vb@pep-project.org>
Thu, 26 Mar 2015 15:30:21 +0100
changeset 130 507895068f83
child 491 d32c60ada438
permissions -rw-r--r--
modifications for Windoze
     1 /******************************************************************************
     2 ** This file is an amalgamation of many separate C source files from SQLite
     3 ** version 3.8.6.  By combining all the individual C code files into this 
     4 ** single large file, the entire code can be compiled as a single translation
     5 ** unit.  This allows many compilers to do optimizations that would not be
     6 ** possible if the files were compiled separately.  Performance improvements
     7 ** of 5% or more are commonly seen when SQLite is compiled as a single
     8 ** translation unit.
     9 **
    10 ** This file is all you need to compile SQLite.  To use SQLite in other
    11 ** programs, you need this file and the "sqlite3.h" header file that defines
    12 ** the programming interface to the SQLite library.  (If you do not have 
    13 ** the "sqlite3.h" header file at hand, you will find a copy embedded within
    14 ** the text of this file.  Search for "Begin file sqlite3.h" to find the start
    15 ** of the embedded sqlite3.h header file.) Additional code files may be needed
    16 ** if you want a wrapper to interface SQLite with your choice of programming
    17 ** language. The code for the "sqlite3" command-line shell is also in a
    18 ** separate file. This file contains only code for the core SQLite library.
    19 */
    20 #define SQLITE_CORE 1
    21 #define SQLITE_AMALGAMATION 1
    22 #ifndef SQLITE_PRIVATE
    23 # define SQLITE_PRIVATE static
    24 #endif
    25 #ifndef SQLITE_API
    26 # define SQLITE_API
    27 #endif
    28 /************** Begin file sqliteInt.h ***************************************/
    29 /*
    30 ** 2001 September 15
    31 **
    32 ** The author disclaims copyright to this source code.  In place of
    33 ** a legal notice, here is a blessing:
    34 **
    35 **    May you do good and not evil.
    36 **    May you find forgiveness for yourself and forgive others.
    37 **    May you share freely, never taking more than you give.
    38 **
    39 *************************************************************************
    40 ** Internal interface definitions for SQLite.
    41 **
    42 */
    43 #ifndef _SQLITEINT_H_
    44 #define _SQLITEINT_H_
    45 
    46 /*
    47 ** These #defines should enable >2GB file support on POSIX if the
    48 ** underlying operating system supports it.  If the OS lacks
    49 ** large file support, or if the OS is windows, these should be no-ops.
    50 **
    51 ** Ticket #2739:  The _LARGEFILE_SOURCE macro must appear before any
    52 ** system #includes.  Hence, this block of code must be the very first
    53 ** code in all source files.
    54 **
    55 ** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
    56 ** on the compiler command line.  This is necessary if you are compiling
    57 ** on a recent machine (ex: Red Hat 7.2) but you want your code to work
    58 ** on an older machine (ex: Red Hat 6.0).  If you compile on Red Hat 7.2
    59 ** without this option, LFS is enable.  But LFS does not exist in the kernel
    60 ** in Red Hat 6.0, so the code won't work.  Hence, for maximum binary
    61 ** portability you should omit LFS.
    62 **
    63 ** The previous paragraph was written in 2005.  (This paragraph is written
    64 ** on 2008-11-28.) These days, all Linux kernels support large files, so
    65 ** you should probably leave LFS enabled.  But some embedded platforms might
    66 ** lack LFS in which case the SQLITE_DISABLE_LFS macro might still be useful.
    67 **
    68 ** Similar is true for Mac OS X.  LFS is only supported on Mac OS X 9 and later.
    69 */
    70 #ifndef SQLITE_DISABLE_LFS
    71 # define _LARGE_FILE       1
    72 # ifndef _FILE_OFFSET_BITS
    73 #   define _FILE_OFFSET_BITS 64
    74 # endif
    75 # define _LARGEFILE_SOURCE 1
    76 #endif
    77 
    78 /*
    79 ** For MinGW, check to see if we can include the header file containing its
    80 ** version information, among other things.  Normally, this internal MinGW
    81 ** header file would [only] be included automatically by other MinGW header
    82 ** files; however, the contained version information is now required by this
    83 ** header file to work around binary compatibility issues (see below) and
    84 ** this is the only known way to reliably obtain it.  This entire #if block
    85 ** would be completely unnecessary if there was any other way of detecting
    86 ** MinGW via their preprocessor (e.g. if they customized their GCC to define
    87 ** some MinGW-specific macros).  When compiling for MinGW, either the
    88 ** _HAVE_MINGW_H or _HAVE__MINGW_H (note the extra underscore) macro must be
    89 ** defined; otherwise, detection of conditions specific to MinGW will be
    90 ** disabled.
    91 */
    92 #if defined(_HAVE_MINGW_H)
    93 # include "mingw.h"
    94 #elif defined(_HAVE__MINGW_H)
    95 # include "_mingw.h"
    96 #endif
    97 
    98 /*
    99 ** For MinGW version 4.x (and higher), check to see if the _USE_32BIT_TIME_T
   100 ** define is required to maintain binary compatibility with the MSVC runtime
   101 ** library in use (e.g. for Windows XP).
   102 */
   103 #if !defined(_USE_32BIT_TIME_T) && !defined(_USE_64BIT_TIME_T) && \
   104     defined(_WIN32) && !defined(_WIN64) && \
   105     defined(__MINGW_MAJOR_VERSION) && __MINGW_MAJOR_VERSION >= 4 && \
   106     defined(__MSVCRT__)
   107 # define _USE_32BIT_TIME_T
   108 #endif
   109 
   110 /* The public SQLite interface.  The _FILE_OFFSET_BITS macro must appear
   111 ** first in QNX.  Also, the _USE_32BIT_TIME_T macro must appear first for
   112 ** MinGW.
   113 */
   114 /************** Include sqlite3.h in the middle of sqliteInt.h ***************/
   115 /************** Begin file sqlite3.h *****************************************/
   116 /*
   117 ** 2001 September 15
   118 **
   119 ** The author disclaims copyright to this source code.  In place of
   120 ** a legal notice, here is a blessing:
   121 **
   122 **    May you do good and not evil.
   123 **    May you find forgiveness for yourself and forgive others.
   124 **    May you share freely, never taking more than you give.
   125 **
   126 *************************************************************************
   127 ** This header file defines the interface that the SQLite library
   128 ** presents to client programs.  If a C-function, structure, datatype,
   129 ** or constant definition does not appear in this file, then it is
   130 ** not a published API of SQLite, is subject to change without
   131 ** notice, and should not be referenced by programs that use SQLite.
   132 **
   133 ** Some of the definitions that are in this file are marked as
   134 ** "experimental".  Experimental interfaces are normally new
   135 ** features recently added to SQLite.  We do not anticipate changes
   136 ** to experimental interfaces but reserve the right to make minor changes
   137 ** if experience from use "in the wild" suggest such changes are prudent.
   138 **
   139 ** The official C-language API documentation for SQLite is derived
   140 ** from comments in this file.  This file is the authoritative source
   141 ** on how SQLite interfaces are suppose to operate.
   142 **
   143 ** The name of this file under configuration management is "sqlite.h.in".
   144 ** The makefile makes some minor changes to this file (such as inserting
   145 ** the version number) and changes its name to "sqlite3.h" as
   146 ** part of the build process.
   147 */
   148 #ifndef _SQLITE3_H_
   149 #define _SQLITE3_H_
   150 #include <stdarg.h>     /* Needed for the definition of va_list */
   151 
   152 /*
   153 ** Make sure we can call this stuff from C++.
   154 */
   155 #if 0
   156 extern "C" {
   157 #endif
   158 
   159 
   160 /*
   161 ** Add the ability to override 'extern'
   162 */
   163 #ifndef SQLITE_EXTERN
   164 # define SQLITE_EXTERN extern
   165 #endif
   166 
   167 #ifndef SQLITE_API
   168 # define SQLITE_API
   169 #endif
   170 
   171 
   172 /*
   173 ** These no-op macros are used in front of interfaces to mark those
   174 ** interfaces as either deprecated or experimental.  New applications
   175 ** should not use deprecated interfaces - they are support for backwards
   176 ** compatibility only.  Application writers should be aware that
   177 ** experimental interfaces are subject to change in point releases.
   178 **
   179 ** These macros used to resolve to various kinds of compiler magic that
   180 ** would generate warning messages when they were used.  But that
   181 ** compiler magic ended up generating such a flurry of bug reports
   182 ** that we have taken it all out and gone back to using simple
   183 ** noop macros.
   184 */
   185 #define SQLITE_DEPRECATED
   186 #define SQLITE_EXPERIMENTAL
   187 
   188 /*
   189 ** Ensure these symbols were not defined by some previous header file.
   190 */
   191 #ifdef SQLITE_VERSION
   192 # undef SQLITE_VERSION
   193 #endif
   194 #ifdef SQLITE_VERSION_NUMBER
   195 # undef SQLITE_VERSION_NUMBER
   196 #endif
   197 
   198 /*
   199 ** CAPI3REF: Compile-Time Library Version Numbers
   200 **
   201 ** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
   202 ** evaluates to a string literal that is the SQLite version in the
   203 ** format "X.Y.Z" where X is the major version number (always 3 for
   204 ** SQLite3) and Y is the minor version number and Z is the release number.)^
   205 ** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
   206 ** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
   207 ** numbers used in [SQLITE_VERSION].)^
   208 ** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
   209 ** be larger than the release from which it is derived.  Either Y will
   210 ** be held constant and Z will be incremented or else Y will be incremented
   211 ** and Z will be reset to zero.
   212 **
   213 ** Since version 3.6.18, SQLite source code has been stored in the
   214 ** <a href="http://www.fossil-scm.org/">Fossil configuration management
   215 ** system</a>.  ^The SQLITE_SOURCE_ID macro evaluates to
   216 ** a string which identifies a particular check-in of SQLite
   217 ** within its configuration management system.  ^The SQLITE_SOURCE_ID
   218 ** string contains the date and time of the check-in (UTC) and an SHA1
   219 ** hash of the entire source tree.
   220 **
   221 ** See also: [sqlite3_libversion()],
   222 ** [sqlite3_libversion_number()], [sqlite3_sourceid()],
   223 ** [sqlite_version()] and [sqlite_source_id()].
   224 */
   225 #define SQLITE_VERSION        "3.8.6"
   226 #define SQLITE_VERSION_NUMBER 3008006
   227 #define SQLITE_SOURCE_ID      "2014-08-15 11:46:33 9491ba7d738528f168657adb43a198238abde19e"
   228 
   229 /*
   230 ** CAPI3REF: Run-Time Library Version Numbers
   231 ** KEYWORDS: sqlite3_version, sqlite3_sourceid
   232 **
   233 ** These interfaces provide the same information as the [SQLITE_VERSION],
   234 ** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
   235 ** but are associated with the library instead of the header file.  ^(Cautious
   236 ** programmers might include assert() statements in their application to
   237 ** verify that values returned by these interfaces match the macros in
   238 ** the header, and thus insure that the application is
   239 ** compiled with matching library and header files.
   240 **
   241 ** <blockquote><pre>
   242 ** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
   243 ** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
   244 ** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
   245 ** </pre></blockquote>)^
   246 **
   247 ** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
   248 ** macro.  ^The sqlite3_libversion() function returns a pointer to the
   249 ** to the sqlite3_version[] string constant.  The sqlite3_libversion()
   250 ** function is provided for use in DLLs since DLL users usually do not have
   251 ** direct access to string constants within the DLL.  ^The
   252 ** sqlite3_libversion_number() function returns an integer equal to
   253 ** [SQLITE_VERSION_NUMBER].  ^The sqlite3_sourceid() function returns 
   254 ** a pointer to a string constant whose value is the same as the 
   255 ** [SQLITE_SOURCE_ID] C preprocessor macro.
   256 **
   257 ** See also: [sqlite_version()] and [sqlite_source_id()].
   258 */
   259 SQLITE_API const char sqlite3_version[] = SQLITE_VERSION;
   260 SQLITE_API const char *sqlite3_libversion(void);
   261 SQLITE_API const char *sqlite3_sourceid(void);
   262 SQLITE_API int sqlite3_libversion_number(void);
   263 
   264 /*
   265 ** CAPI3REF: Run-Time Library Compilation Options Diagnostics
   266 **
   267 ** ^The sqlite3_compileoption_used() function returns 0 or 1 
   268 ** indicating whether the specified option was defined at 
   269 ** compile time.  ^The SQLITE_ prefix may be omitted from the 
   270 ** option name passed to sqlite3_compileoption_used().  
   271 **
   272 ** ^The sqlite3_compileoption_get() function allows iterating
   273 ** over the list of options that were defined at compile time by
   274 ** returning the N-th compile time option string.  ^If N is out of range,
   275 ** sqlite3_compileoption_get() returns a NULL pointer.  ^The SQLITE_ 
   276 ** prefix is omitted from any strings returned by 
   277 ** sqlite3_compileoption_get().
   278 **
   279 ** ^Support for the diagnostic functions sqlite3_compileoption_used()
   280 ** and sqlite3_compileoption_get() may be omitted by specifying the 
   281 ** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
   282 **
   283 ** See also: SQL functions [sqlite_compileoption_used()] and
   284 ** [sqlite_compileoption_get()] and the [compile_options pragma].
   285 */
   286 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
   287 SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
   288 SQLITE_API const char *sqlite3_compileoption_get(int N);
   289 #endif
   290 
   291 /*
   292 ** CAPI3REF: Test To See If The Library Is Threadsafe
   293 **
   294 ** ^The sqlite3_threadsafe() function returns zero if and only if
   295 ** SQLite was compiled with mutexing code omitted due to the
   296 ** [SQLITE_THREADSAFE] compile-time option being set to 0.
   297 **
   298 ** SQLite can be compiled with or without mutexes.  When
   299 ** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
   300 ** are enabled and SQLite is threadsafe.  When the
   301 ** [SQLITE_THREADSAFE] macro is 0, 
   302 ** the mutexes are omitted.  Without the mutexes, it is not safe
   303 ** to use SQLite concurrently from more than one thread.
   304 **
   305 ** Enabling mutexes incurs a measurable performance penalty.
   306 ** So if speed is of utmost importance, it makes sense to disable
   307 ** the mutexes.  But for maximum safety, mutexes should be enabled.
   308 ** ^The default behavior is for mutexes to be enabled.
   309 **
   310 ** This interface can be used by an application to make sure that the
   311 ** version of SQLite that it is linking against was compiled with
   312 ** the desired setting of the [SQLITE_THREADSAFE] macro.
   313 **
   314 ** This interface only reports on the compile-time mutex setting
   315 ** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
   316 ** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
   317 ** can be fully or partially disabled using a call to [sqlite3_config()]
   318 ** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
   319 ** or [SQLITE_CONFIG_MUTEX].  ^(The return value of the
   320 ** sqlite3_threadsafe() function shows only the compile-time setting of
   321 ** thread safety, not any run-time changes to that setting made by
   322 ** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
   323 ** is unchanged by calls to sqlite3_config().)^
   324 **
   325 ** See the [threading mode] documentation for additional information.
   326 */
   327 SQLITE_API int sqlite3_threadsafe(void);
   328 
   329 /*
   330 ** CAPI3REF: Database Connection Handle
   331 ** KEYWORDS: {database connection} {database connections}
   332 **
   333 ** Each open SQLite database is represented by a pointer to an instance of
   334 ** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
   335 ** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
   336 ** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
   337 ** and [sqlite3_close_v2()] are its destructors.  There are many other
   338 ** interfaces (such as
   339 ** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
   340 ** [sqlite3_busy_timeout()] to name but three) that are methods on an
   341 ** sqlite3 object.
   342 */
   343 typedef struct sqlite3 sqlite3;
   344 
   345 /*
   346 ** CAPI3REF: 64-Bit Integer Types
   347 ** KEYWORDS: sqlite_int64 sqlite_uint64
   348 **
   349 ** Because there is no cross-platform way to specify 64-bit integer types
   350 ** SQLite includes typedefs for 64-bit signed and unsigned integers.
   351 **
   352 ** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
   353 ** The sqlite_int64 and sqlite_uint64 types are supported for backwards
   354 ** compatibility only.
   355 **
   356 ** ^The sqlite3_int64 and sqlite_int64 types can store integer values
   357 ** between -9223372036854775808 and +9223372036854775807 inclusive.  ^The
   358 ** sqlite3_uint64 and sqlite_uint64 types can store integer values 
   359 ** between 0 and +18446744073709551615 inclusive.
   360 */
   361 #ifdef SQLITE_INT64_TYPE
   362   typedef SQLITE_INT64_TYPE sqlite_int64;
   363   typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
   364 #elif defined(_MSC_VER) || defined(__BORLANDC__)
   365   typedef __int64 sqlite_int64;
   366   typedef unsigned __int64 sqlite_uint64;
   367 #else
   368   typedef long long int sqlite_int64;
   369   typedef unsigned long long int sqlite_uint64;
   370 #endif
   371 typedef sqlite_int64 sqlite3_int64;
   372 typedef sqlite_uint64 sqlite3_uint64;
   373 
   374 /*
   375 ** If compiling for a processor that lacks floating point support,
   376 ** substitute integer for floating-point.
   377 */
   378 #ifdef SQLITE_OMIT_FLOATING_POINT
   379 # define double sqlite3_int64
   380 #endif
   381 
   382 /*
   383 ** CAPI3REF: Closing A Database Connection
   384 **
   385 ** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
   386 ** for the [sqlite3] object.
   387 ** ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if
   388 ** the [sqlite3] object is successfully destroyed and all associated
   389 ** resources are deallocated.
   390 **
   391 ** ^If the database connection is associated with unfinalized prepared
   392 ** statements or unfinished sqlite3_backup objects then sqlite3_close()
   393 ** will leave the database connection open and return [SQLITE_BUSY].
   394 ** ^If sqlite3_close_v2() is called with unfinalized prepared statements
   395 ** and/or unfinished sqlite3_backups, then the database connection becomes
   396 ** an unusable "zombie" which will automatically be deallocated when the
   397 ** last prepared statement is finalized or the last sqlite3_backup is
   398 ** finished.  The sqlite3_close_v2() interface is intended for use with
   399 ** host languages that are garbage collected, and where the order in which
   400 ** destructors are called is arbitrary.
   401 **
   402 ** Applications should [sqlite3_finalize | finalize] all [prepared statements],
   403 ** [sqlite3_blob_close | close] all [BLOB handles], and 
   404 ** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
   405 ** with the [sqlite3] object prior to attempting to close the object.  ^If
   406 ** sqlite3_close_v2() is called on a [database connection] that still has
   407 ** outstanding [prepared statements], [BLOB handles], and/or
   408 ** [sqlite3_backup] objects then it returns [SQLITE_OK] and the deallocation
   409 ** of resources is deferred until all [prepared statements], [BLOB handles],
   410 ** and [sqlite3_backup] objects are also destroyed.
   411 **
   412 ** ^If an [sqlite3] object is destroyed while a transaction is open,
   413 ** the transaction is automatically rolled back.
   414 **
   415 ** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
   416 ** must be either a NULL
   417 ** pointer or an [sqlite3] object pointer obtained
   418 ** from [sqlite3_open()], [sqlite3_open16()], or
   419 ** [sqlite3_open_v2()], and not previously closed.
   420 ** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
   421 ** argument is a harmless no-op.
   422 */
   423 SQLITE_API int sqlite3_close(sqlite3*);
   424 SQLITE_API int sqlite3_close_v2(sqlite3*);
   425 
   426 /*
   427 ** The type for a callback function.
   428 ** This is legacy and deprecated.  It is included for historical
   429 ** compatibility and is not documented.
   430 */
   431 typedef int (*sqlite3_callback)(void*,int,char**, char**);
   432 
   433 /*
   434 ** CAPI3REF: One-Step Query Execution Interface
   435 **
   436 ** The sqlite3_exec() interface is a convenience wrapper around
   437 ** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
   438 ** that allows an application to run multiple statements of SQL
   439 ** without having to use a lot of C code. 
   440 **
   441 ** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
   442 ** semicolon-separate SQL statements passed into its 2nd argument,
   443 ** in the context of the [database connection] passed in as its 1st
   444 ** argument.  ^If the callback function of the 3rd argument to
   445 ** sqlite3_exec() is not NULL, then it is invoked for each result row
   446 ** coming out of the evaluated SQL statements.  ^The 4th argument to
   447 ** sqlite3_exec() is relayed through to the 1st argument of each
   448 ** callback invocation.  ^If the callback pointer to sqlite3_exec()
   449 ** is NULL, then no callback is ever invoked and result rows are
   450 ** ignored.
   451 **
   452 ** ^If an error occurs while evaluating the SQL statements passed into
   453 ** sqlite3_exec(), then execution of the current statement stops and
   454 ** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
   455 ** is not NULL then any error message is written into memory obtained
   456 ** from [sqlite3_malloc()] and passed back through the 5th parameter.
   457 ** To avoid memory leaks, the application should invoke [sqlite3_free()]
   458 ** on error message strings returned through the 5th parameter of
   459 ** of sqlite3_exec() after the error message string is no longer needed.
   460 ** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
   461 ** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
   462 ** NULL before returning.
   463 **
   464 ** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
   465 ** routine returns SQLITE_ABORT without invoking the callback again and
   466 ** without running any subsequent SQL statements.
   467 **
   468 ** ^The 2nd argument to the sqlite3_exec() callback function is the
   469 ** number of columns in the result.  ^The 3rd argument to the sqlite3_exec()
   470 ** callback is an array of pointers to strings obtained as if from
   471 ** [sqlite3_column_text()], one for each column.  ^If an element of a
   472 ** result row is NULL then the corresponding string pointer for the
   473 ** sqlite3_exec() callback is a NULL pointer.  ^The 4th argument to the
   474 ** sqlite3_exec() callback is an array of pointers to strings where each
   475 ** entry represents the name of corresponding result column as obtained
   476 ** from [sqlite3_column_name()].
   477 **
   478 ** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
   479 ** to an empty string, or a pointer that contains only whitespace and/or 
   480 ** SQL comments, then no SQL statements are evaluated and the database
   481 ** is not changed.
   482 **
   483 ** Restrictions:
   484 **
   485 ** <ul>
   486 ** <li> The application must insure that the 1st parameter to sqlite3_exec()
   487 **      is a valid and open [database connection].
   488 ** <li> The application must not close the [database connection] specified by
   489 **      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
   490 ** <li> The application must not modify the SQL statement text passed into
   491 **      the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
   492 ** </ul>
   493 */
   494 SQLITE_API int sqlite3_exec(
   495   sqlite3*,                                  /* An open database */
   496   const char *sql,                           /* SQL to be evaluated */
   497   int (*callback)(void*,int,char**,char**),  /* Callback function */
   498   void *,                                    /* 1st argument to callback */
   499   char **errmsg                              /* Error msg written here */
   500 );
   501 
   502 /*
   503 ** CAPI3REF: Result Codes
   504 ** KEYWORDS: {result code definitions}
   505 **
   506 ** Many SQLite functions return an integer result code from the set shown
   507 ** here in order to indicate success or failure.
   508 **
   509 ** New error codes may be added in future versions of SQLite.
   510 **
   511 ** See also: [extended result code definitions]
   512 */
   513 #define SQLITE_OK           0   /* Successful result */
   514 /* beginning-of-error-codes */
   515 #define SQLITE_ERROR        1   /* SQL error or missing database */
   516 #define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
   517 #define SQLITE_PERM         3   /* Access permission denied */
   518 #define SQLITE_ABORT        4   /* Callback routine requested an abort */
   519 #define SQLITE_BUSY         5   /* The database file is locked */
   520 #define SQLITE_LOCKED       6   /* A table in the database is locked */
   521 #define SQLITE_NOMEM        7   /* A malloc() failed */
   522 #define SQLITE_READONLY     8   /* Attempt to write a readonly database */
   523 #define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
   524 #define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
   525 #define SQLITE_CORRUPT     11   /* The database disk image is malformed */
   526 #define SQLITE_NOTFOUND    12   /* Unknown opcode in sqlite3_file_control() */
   527 #define SQLITE_FULL        13   /* Insertion failed because database is full */
   528 #define SQLITE_CANTOPEN    14   /* Unable to open the database file */
   529 #define SQLITE_PROTOCOL    15   /* Database lock protocol error */
   530 #define SQLITE_EMPTY       16   /* Database is empty */
   531 #define SQLITE_SCHEMA      17   /* The database schema changed */
   532 #define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
   533 #define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
   534 #define SQLITE_MISMATCH    20   /* Data type mismatch */
   535 #define SQLITE_MISUSE      21   /* Library used incorrectly */
   536 #define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
   537 #define SQLITE_AUTH        23   /* Authorization denied */
   538 #define SQLITE_FORMAT      24   /* Auxiliary database format error */
   539 #define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
   540 #define SQLITE_NOTADB      26   /* File opened that is not a database file */
   541 #define SQLITE_NOTICE      27   /* Notifications from sqlite3_log() */
   542 #define SQLITE_WARNING     28   /* Warnings from sqlite3_log() */
   543 #define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
   544 #define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
   545 /* end-of-error-codes */
   546 
   547 /*
   548 ** CAPI3REF: Extended Result Codes
   549 ** KEYWORDS: {extended result code definitions}
   550 **
   551 ** In its default configuration, SQLite API routines return one of 30 integer
   552 ** [result codes].  However, experience has shown that many of
   553 ** these result codes are too coarse-grained.  They do not provide as
   554 ** much information about problems as programmers might like.  In an effort to
   555 ** address this, newer versions of SQLite (version 3.3.8 and later) include
   556 ** support for additional result codes that provide more detailed information
   557 ** about errors. These [extended result codes] are enabled or disabled
   558 ** on a per database connection basis using the
   559 ** [sqlite3_extended_result_codes()] API.  Or, the extended code for
   560 ** the most recent error can be obtained using
   561 ** [sqlite3_extended_errcode()].
   562 */
   563 #define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
   564 #define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
   565 #define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
   566 #define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
   567 #define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
   568 #define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
   569 #define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
   570 #define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
   571 #define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
   572 #define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
   573 #define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
   574 #define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
   575 #define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
   576 #define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
   577 #define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
   578 #define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
   579 #define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
   580 #define SQLITE_IOERR_SHMOPEN           (SQLITE_IOERR | (18<<8))
   581 #define SQLITE_IOERR_SHMSIZE           (SQLITE_IOERR | (19<<8))
   582 #define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
   583 #define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
   584 #define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
   585 #define SQLITE_IOERR_DELETE_NOENT      (SQLITE_IOERR | (23<<8))
   586 #define SQLITE_IOERR_MMAP              (SQLITE_IOERR | (24<<8))
   587 #define SQLITE_IOERR_GETTEMPPATH       (SQLITE_IOERR | (25<<8))
   588 #define SQLITE_IOERR_CONVPATH          (SQLITE_IOERR | (26<<8))
   589 #define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
   590 #define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
   591 #define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
   592 #define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
   593 #define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
   594 #define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
   595 #define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
   596 #define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
   597 #define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
   598 #define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
   599 #define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
   600 #define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
   601 #define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
   602 #define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
   603 #define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
   604 #define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
   605 #define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
   606 #define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
   607 #define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))
   608 #define SQLITE_CONSTRAINT_TRIGGER      (SQLITE_CONSTRAINT | (7<<8))
   609 #define SQLITE_CONSTRAINT_UNIQUE       (SQLITE_CONSTRAINT | (8<<8))
   610 #define SQLITE_CONSTRAINT_VTAB         (SQLITE_CONSTRAINT | (9<<8))
   611 #define SQLITE_CONSTRAINT_ROWID        (SQLITE_CONSTRAINT |(10<<8))
   612 #define SQLITE_NOTICE_RECOVER_WAL      (SQLITE_NOTICE | (1<<8))
   613 #define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))
   614 #define SQLITE_WARNING_AUTOINDEX       (SQLITE_WARNING | (1<<8))
   615 
   616 /*
   617 ** CAPI3REF: Flags For File Open Operations
   618 **
   619 ** These bit values are intended for use in the
   620 ** 3rd parameter to the [sqlite3_open_v2()] interface and
   621 ** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
   622 */
   623 #define SQLITE_OPEN_READONLY         0x00000001  /* Ok for sqlite3_open_v2() */
   624 #define SQLITE_OPEN_READWRITE        0x00000002  /* Ok for sqlite3_open_v2() */
   625 #define SQLITE_OPEN_CREATE           0x00000004  /* Ok for sqlite3_open_v2() */
   626 #define SQLITE_OPEN_DELETEONCLOSE    0x00000008  /* VFS only */
   627 #define SQLITE_OPEN_EXCLUSIVE        0x00000010  /* VFS only */
   628 #define SQLITE_OPEN_AUTOPROXY        0x00000020  /* VFS only */
   629 #define SQLITE_OPEN_URI              0x00000040  /* Ok for sqlite3_open_v2() */
   630 #define SQLITE_OPEN_MEMORY           0x00000080  /* Ok for sqlite3_open_v2() */
   631 #define SQLITE_OPEN_MAIN_DB          0x00000100  /* VFS only */
   632 #define SQLITE_OPEN_TEMP_DB          0x00000200  /* VFS only */
   633 #define SQLITE_OPEN_TRANSIENT_DB     0x00000400  /* VFS only */
   634 #define SQLITE_OPEN_MAIN_JOURNAL     0x00000800  /* VFS only */
   635 #define SQLITE_OPEN_TEMP_JOURNAL     0x00001000  /* VFS only */
   636 #define SQLITE_OPEN_SUBJOURNAL       0x00002000  /* VFS only */
   637 #define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
   638 #define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
   639 #define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
   640 #define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
   641 #define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
   642 #define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
   643 
   644 /* Reserved:                         0x00F00000 */
   645 
   646 /*
   647 ** CAPI3REF: Device Characteristics
   648 **
   649 ** The xDeviceCharacteristics method of the [sqlite3_io_methods]
   650 ** object returns an integer which is a vector of these
   651 ** bit values expressing I/O characteristics of the mass storage
   652 ** device that holds the file that the [sqlite3_io_methods]
   653 ** refers to.
   654 **
   655 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   656 ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   657 ** mean that writes of blocks that are nnn bytes in size and
   658 ** are aligned to an address which is an integer multiple of
   659 ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   660 ** that when data is appended to a file, the data is appended
   661 ** first then the size of the file is extended, never the other
   662 ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   663 ** information is written to disk in the same order as calls
   664 ** to xWrite().  The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
   665 ** after reboot following a crash or power loss, the only bytes in a
   666 ** file that were written at the application level might have changed
   667 ** and that adjacent bytes, even bytes within the same sector are
   668 ** guaranteed to be unchanged.  The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
   669 ** flag indicate that a file cannot be deleted when open.  The
   670 ** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
   671 ** read-only media and cannot be changed even by processes with
   672 ** elevated privileges.
   673 */
   674 #define SQLITE_IOCAP_ATOMIC                 0x00000001
   675 #define SQLITE_IOCAP_ATOMIC512              0x00000002
   676 #define SQLITE_IOCAP_ATOMIC1K               0x00000004
   677 #define SQLITE_IOCAP_ATOMIC2K               0x00000008
   678 #define SQLITE_IOCAP_ATOMIC4K               0x00000010
   679 #define SQLITE_IOCAP_ATOMIC8K               0x00000020
   680 #define SQLITE_IOCAP_ATOMIC16K              0x00000040
   681 #define SQLITE_IOCAP_ATOMIC32K              0x00000080
   682 #define SQLITE_IOCAP_ATOMIC64K              0x00000100
   683 #define SQLITE_IOCAP_SAFE_APPEND            0x00000200
   684 #define SQLITE_IOCAP_SEQUENTIAL             0x00000400
   685 #define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800
   686 #define SQLITE_IOCAP_POWERSAFE_OVERWRITE    0x00001000
   687 #define SQLITE_IOCAP_IMMUTABLE              0x00002000
   688 
   689 /*
   690 ** CAPI3REF: File Locking Levels
   691 **
   692 ** SQLite uses one of these integer values as the second
   693 ** argument to calls it makes to the xLock() and xUnlock() methods
   694 ** of an [sqlite3_io_methods] object.
   695 */
   696 #define SQLITE_LOCK_NONE          0
   697 #define SQLITE_LOCK_SHARED        1
   698 #define SQLITE_LOCK_RESERVED      2
   699 #define SQLITE_LOCK_PENDING       3
   700 #define SQLITE_LOCK_EXCLUSIVE     4
   701 
   702 /*
   703 ** CAPI3REF: Synchronization Type Flags
   704 **
   705 ** When SQLite invokes the xSync() method of an
   706 ** [sqlite3_io_methods] object it uses a combination of
   707 ** these integer values as the second argument.
   708 **
   709 ** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
   710 ** sync operation only needs to flush data to mass storage.  Inode
   711 ** information need not be flushed. If the lower four bits of the flag
   712 ** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
   713 ** If the lower four bits equal SQLITE_SYNC_FULL, that means
   714 ** to use Mac OS X style fullsync instead of fsync().
   715 **
   716 ** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
   717 ** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
   718 ** settings.  The [synchronous pragma] determines when calls to the
   719 ** xSync VFS method occur and applies uniformly across all platforms.
   720 ** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
   721 ** energetic or rigorous or forceful the sync operations are and
   722 ** only make a difference on Mac OSX for the default SQLite code.
   723 ** (Third-party VFS implementations might also make the distinction
   724 ** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
   725 ** operating systems natively supported by SQLite, only Mac OSX
   726 ** cares about the difference.)
   727 */
   728 #define SQLITE_SYNC_NORMAL        0x00002
   729 #define SQLITE_SYNC_FULL          0x00003
   730 #define SQLITE_SYNC_DATAONLY      0x00010
   731 
   732 /*
   733 ** CAPI3REF: OS Interface Open File Handle
   734 **
   735 ** An [sqlite3_file] object represents an open file in the 
   736 ** [sqlite3_vfs | OS interface layer].  Individual OS interface
   737 ** implementations will
   738 ** want to subclass this object by appending additional fields
   739 ** for their own use.  The pMethods entry is a pointer to an
   740 ** [sqlite3_io_methods] object that defines methods for performing
   741 ** I/O operations on the open file.
   742 */
   743 typedef struct sqlite3_file sqlite3_file;
   744 struct sqlite3_file {
   745   const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
   746 };
   747 
   748 /*
   749 ** CAPI3REF: OS Interface File Virtual Methods Object
   750 **
   751 ** Every file opened by the [sqlite3_vfs.xOpen] method populates an
   752 ** [sqlite3_file] object (or, more commonly, a subclass of the
   753 ** [sqlite3_file] object) with a pointer to an instance of this object.
   754 ** This object defines the methods used to perform various operations
   755 ** against the open file represented by the [sqlite3_file] object.
   756 **
   757 ** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element 
   758 ** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
   759 ** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed.  The
   760 ** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
   761 ** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
   762 ** to NULL.
   763 **
   764 ** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
   765 ** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
   766 ** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
   767 ** flag may be ORed in to indicate that only the data of the file
   768 ** and not its inode needs to be synced.
   769 **
   770 ** The integer values to xLock() and xUnlock() are one of
   771 ** <ul>
   772 ** <li> [SQLITE_LOCK_NONE],
   773 ** <li> [SQLITE_LOCK_SHARED],
   774 ** <li> [SQLITE_LOCK_RESERVED],
   775 ** <li> [SQLITE_LOCK_PENDING], or
   776 ** <li> [SQLITE_LOCK_EXCLUSIVE].
   777 ** </ul>
   778 ** xLock() increases the lock. xUnlock() decreases the lock.
   779 ** The xCheckReservedLock() method checks whether any database connection,
   780 ** either in this process or in some other process, is holding a RESERVED,
   781 ** PENDING, or EXCLUSIVE lock on the file.  It returns true
   782 ** if such a lock exists and false otherwise.
   783 **
   784 ** The xFileControl() method is a generic interface that allows custom
   785 ** VFS implementations to directly control an open file using the
   786 ** [sqlite3_file_control()] interface.  The second "op" argument is an
   787 ** integer opcode.  The third argument is a generic pointer intended to
   788 ** point to a structure that may contain arguments or space in which to
   789 ** write return values.  Potential uses for xFileControl() might be
   790 ** functions to enable blocking locks with timeouts, to change the
   791 ** locking strategy (for example to use dot-file locks), to inquire
   792 ** about the status of a lock, or to break stale locks.  The SQLite
   793 ** core reserves all opcodes less than 100 for its own use.
   794 ** A [file control opcodes | list of opcodes] less than 100 is available.
   795 ** Applications that define a custom xFileControl method should use opcodes
   796 ** greater than 100 to avoid conflicts.  VFS implementations should
   797 ** return [SQLITE_NOTFOUND] for file control opcodes that they do not
   798 ** recognize.
   799 **
   800 ** The xSectorSize() method returns the sector size of the
   801 ** device that underlies the file.  The sector size is the
   802 ** minimum write that can be performed without disturbing
   803 ** other bytes in the file.  The xDeviceCharacteristics()
   804 ** method returns a bit vector describing behaviors of the
   805 ** underlying device:
   806 **
   807 ** <ul>
   808 ** <li> [SQLITE_IOCAP_ATOMIC]
   809 ** <li> [SQLITE_IOCAP_ATOMIC512]
   810 ** <li> [SQLITE_IOCAP_ATOMIC1K]
   811 ** <li> [SQLITE_IOCAP_ATOMIC2K]
   812 ** <li> [SQLITE_IOCAP_ATOMIC4K]
   813 ** <li> [SQLITE_IOCAP_ATOMIC8K]
   814 ** <li> [SQLITE_IOCAP_ATOMIC16K]
   815 ** <li> [SQLITE_IOCAP_ATOMIC32K]
   816 ** <li> [SQLITE_IOCAP_ATOMIC64K]
   817 ** <li> [SQLITE_IOCAP_SAFE_APPEND]
   818 ** <li> [SQLITE_IOCAP_SEQUENTIAL]
   819 ** </ul>
   820 **
   821 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   822 ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   823 ** mean that writes of blocks that are nnn bytes in size and
   824 ** are aligned to an address which is an integer multiple of
   825 ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   826 ** that when data is appended to a file, the data is appended
   827 ** first then the size of the file is extended, never the other
   828 ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   829 ** information is written to disk in the same order as calls
   830 ** to xWrite().
   831 **
   832 ** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
   833 ** in the unread portions of the buffer with zeros.  A VFS that
   834 ** fails to zero-fill short reads might seem to work.  However,
   835 ** failure to zero-fill short reads will eventually lead to
   836 ** database corruption.
   837 */
   838 typedef struct sqlite3_io_methods sqlite3_io_methods;
   839 struct sqlite3_io_methods {
   840   int iVersion;
   841   int (*xClose)(sqlite3_file*);
   842   int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
   843   int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
   844   int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
   845   int (*xSync)(sqlite3_file*, int flags);
   846   int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
   847   int (*xLock)(sqlite3_file*, int);
   848   int (*xUnlock)(sqlite3_file*, int);
   849   int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
   850   int (*xFileControl)(sqlite3_file*, int op, void *pArg);
   851   int (*xSectorSize)(sqlite3_file*);
   852   int (*xDeviceCharacteristics)(sqlite3_file*);
   853   /* Methods above are valid for version 1 */
   854   int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
   855   int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
   856   void (*xShmBarrier)(sqlite3_file*);
   857   int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
   858   /* Methods above are valid for version 2 */
   859   int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
   860   int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
   861   /* Methods above are valid for version 3 */
   862   /* Additional methods may be added in future releases */
   863 };
   864 
   865 /*
   866 ** CAPI3REF: Standard File Control Opcodes
   867 ** KEYWORDS: {file control opcodes} {file control opcode}
   868 **
   869 ** These integer constants are opcodes for the xFileControl method
   870 ** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
   871 ** interface.
   872 **
   873 ** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
   874 ** opcode causes the xFileControl method to write the current state of
   875 ** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
   876 ** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
   877 ** into an integer that the pArg argument points to. This capability
   878 ** is used during testing and only needs to be supported when SQLITE_TEST
   879 ** is defined.
   880 ** <ul>
   881 ** <li>[[SQLITE_FCNTL_SIZE_HINT]]
   882 ** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
   883 ** layer a hint of how large the database file will grow to be during the
   884 ** current transaction.  This hint is not guaranteed to be accurate but it
   885 ** is often close.  The underlying VFS might choose to preallocate database
   886 ** file space based on this hint in order to help writes to the database
   887 ** file run faster.
   888 **
   889 ** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]
   890 ** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
   891 ** extends and truncates the database file in chunks of a size specified
   892 ** by the user. The fourth argument to [sqlite3_file_control()] should 
   893 ** point to an integer (type int) containing the new chunk-size to use
   894 ** for the nominated database. Allocating database file space in large
   895 ** chunks (say 1MB at a time), may reduce file-system fragmentation and
   896 ** improve performance on some systems.
   897 **
   898 ** <li>[[SQLITE_FCNTL_FILE_POINTER]]
   899 ** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
   900 ** to the [sqlite3_file] object associated with a particular database
   901 ** connection.  See the [sqlite3_file_control()] documentation for
   902 ** additional information.
   903 **
   904 ** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]
   905 ** No longer in use.
   906 **
   907 ** <li>[[SQLITE_FCNTL_SYNC]]
   908 ** The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and
   909 ** sent to the VFS immediately before the xSync method is invoked on a
   910 ** database file descriptor. Or, if the xSync method is not invoked 
   911 ** because the user has configured SQLite with 
   912 ** [PRAGMA synchronous | PRAGMA synchronous=OFF] it is invoked in place 
   913 ** of the xSync method. In most cases, the pointer argument passed with
   914 ** this file-control is NULL. However, if the database file is being synced
   915 ** as part of a multi-database commit, the argument points to a nul-terminated
   916 ** string containing the transactions master-journal file name. VFSes that 
   917 ** do not need this signal should silently ignore this opcode. Applications 
   918 ** should not call [sqlite3_file_control()] with this opcode as doing so may 
   919 ** disrupt the operation of the specialized VFSes that do require it.  
   920 **
   921 ** <li>[[SQLITE_FCNTL_COMMIT_PHASETWO]]
   922 ** The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite
   923 ** and sent to the VFS after a transaction has been committed immediately
   924 ** but before the database is unlocked. VFSes that do not need this signal
   925 ** should silently ignore this opcode. Applications should not call
   926 ** [sqlite3_file_control()] with this opcode as doing so may disrupt the 
   927 ** operation of the specialized VFSes that do require it.  
   928 **
   929 ** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]
   930 ** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
   931 ** retry counts and intervals for certain disk I/O operations for the
   932 ** windows [VFS] in order to provide robustness in the presence of
   933 ** anti-virus programs.  By default, the windows VFS will retry file read,
   934 ** file write, and file delete operations up to 10 times, with a delay
   935 ** of 25 milliseconds before the first retry and with the delay increasing
   936 ** by an additional 25 milliseconds with each subsequent retry.  This
   937 ** opcode allows these two values (10 retries and 25 milliseconds of delay)
   938 ** to be adjusted.  The values are changed for all database connections
   939 ** within the same process.  The argument is a pointer to an array of two
   940 ** integers where the first integer i the new retry count and the second
   941 ** integer is the delay.  If either integer is negative, then the setting
   942 ** is not changed but instead the prior value of that setting is written
   943 ** into the array entry, allowing the current retry settings to be
   944 ** interrogated.  The zDbName parameter is ignored.
   945 **
   946 ** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
   947 ** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
   948 ** persistent [WAL | Write Ahead Log] setting.  By default, the auxiliary
   949 ** write ahead log and shared memory files used for transaction control
   950 ** are automatically deleted when the latest connection to the database
   951 ** closes.  Setting persistent WAL mode causes those files to persist after
   952 ** close.  Persisting the files is useful when other processes that do not
   953 ** have write permission on the directory containing the database file want
   954 ** to read the database file, as the WAL and shared memory files must exist
   955 ** in order for the database to be readable.  The fourth parameter to
   956 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
   957 ** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
   958 ** WAL mode.  If the integer is -1, then it is overwritten with the current
   959 ** WAL persistence setting.
   960 **
   961 ** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]
   962 ** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
   963 ** persistent "powersafe-overwrite" or "PSOW" setting.  The PSOW setting
   964 ** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
   965 ** xDeviceCharacteristics methods. The fourth parameter to
   966 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
   967 ** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
   968 ** mode.  If the integer is -1, then it is overwritten with the current
   969 ** zero-damage mode setting.
   970 **
   971 ** <li>[[SQLITE_FCNTL_OVERWRITE]]
   972 ** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
   973 ** a write transaction to indicate that, unless it is rolled back for some
   974 ** reason, the entire database file will be overwritten by the current 
   975 ** transaction. This is used by VACUUM operations.
   976 **
   977 ** <li>[[SQLITE_FCNTL_VFSNAME]]
   978 ** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
   979 ** all [VFSes] in the VFS stack.  The names are of all VFS shims and the
   980 ** final bottom-level VFS are written into memory obtained from 
   981 ** [sqlite3_malloc()] and the result is stored in the char* variable
   982 ** that the fourth parameter of [sqlite3_file_control()] points to.
   983 ** The caller is responsible for freeing the memory when done.  As with
   984 ** all file-control actions, there is no guarantee that this will actually
   985 ** do anything.  Callers should initialize the char* variable to a NULL
   986 ** pointer in case this file-control is not implemented.  This file-control
   987 ** is intended for diagnostic use only.
   988 **
   989 ** <li>[[SQLITE_FCNTL_PRAGMA]]
   990 ** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA] 
   991 ** file control is sent to the open [sqlite3_file] object corresponding
   992 ** to the database file to which the pragma statement refers. ^The argument
   993 ** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
   994 ** pointers to strings (char**) in which the second element of the array
   995 ** is the name of the pragma and the third element is the argument to the
   996 ** pragma or NULL if the pragma has no argument.  ^The handler for an
   997 ** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
   998 ** of the char** argument point to a string obtained from [sqlite3_mprintf()]
   999 ** or the equivalent and that string will become the result of the pragma or
  1000 ** the error message if the pragma fails. ^If the
  1001 ** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal 
  1002 ** [PRAGMA] processing continues.  ^If the [SQLITE_FCNTL_PRAGMA]
  1003 ** file control returns [SQLITE_OK], then the parser assumes that the
  1004 ** VFS has handled the PRAGMA itself and the parser generates a no-op
  1005 ** prepared statement.  ^If the [SQLITE_FCNTL_PRAGMA] file control returns
  1006 ** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
  1007 ** that the VFS encountered an error while handling the [PRAGMA] and the
  1008 ** compilation of the PRAGMA fails with an error.  ^The [SQLITE_FCNTL_PRAGMA]
  1009 ** file control occurs at the beginning of pragma statement analysis and so
  1010 ** it is able to override built-in [PRAGMA] statements.
  1011 **
  1012 ** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
  1013 ** ^The [SQLITE_FCNTL_BUSYHANDLER]
  1014 ** file-control may be invoked by SQLite on the database file handle
  1015 ** shortly after it is opened in order to provide a custom VFS with access
  1016 ** to the connections busy-handler callback. The argument is of type (void **)
  1017 ** - an array of two (void *) values. The first (void *) actually points
  1018 ** to a function of type (int (*)(void *)). In order to invoke the connections
  1019 ** busy-handler, this function should be invoked with the second (void *) in
  1020 ** the array as the only argument. If it returns non-zero, then the operation
  1021 ** should be retried. If it returns zero, the custom VFS should abandon the
  1022 ** current operation.
  1023 **
  1024 ** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
  1025 ** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
  1026 ** to have SQLite generate a
  1027 ** temporary filename using the same algorithm that is followed to generate
  1028 ** temporary filenames for TEMP tables and other internal uses.  The
  1029 ** argument should be a char** which will be filled with the filename
  1030 ** written into memory obtained from [sqlite3_malloc()].  The caller should
  1031 ** invoke [sqlite3_free()] on the result to avoid a memory leak.
  1032 **
  1033 ** <li>[[SQLITE_FCNTL_MMAP_SIZE]]
  1034 ** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
  1035 ** maximum number of bytes that will be used for memory-mapped I/O.
  1036 ** The argument is a pointer to a value of type sqlite3_int64 that
  1037 ** is an advisory maximum number of bytes in the file to memory map.  The
  1038 ** pointer is overwritten with the old value.  The limit is not changed if
  1039 ** the value originally pointed to is negative, and so the current limit 
  1040 ** can be queried by passing in a pointer to a negative number.  This
  1041 ** file-control is used internally to implement [PRAGMA mmap_size].
  1042 **
  1043 ** <li>[[SQLITE_FCNTL_TRACE]]
  1044 ** The [SQLITE_FCNTL_TRACE] file control provides advisory information
  1045 ** to the VFS about what the higher layers of the SQLite stack are doing.
  1046 ** This file control is used by some VFS activity tracing [shims].
  1047 ** The argument is a zero-terminated string.  Higher layers in the
  1048 ** SQLite stack may generate instances of this file control if
  1049 ** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.
  1050 **
  1051 ** <li>[[SQLITE_FCNTL_HAS_MOVED]]
  1052 ** The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a
  1053 ** pointer to an integer and it writes a boolean into that integer depending
  1054 ** on whether or not the file has been renamed, moved, or deleted since it
  1055 ** was first opened.
  1056 **
  1057 ** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]
  1058 ** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging.  This
  1059 ** opcode causes the xFileControl method to swap the file handle with the one
  1060 ** pointed to by the pArg argument.  This capability is used during testing
  1061 ** and only needs to be supported when SQLITE_TEST is defined.
  1062 **
  1063 ** </ul>
  1064 */
  1065 #define SQLITE_FCNTL_LOCKSTATE               1
  1066 #define SQLITE_GET_LOCKPROXYFILE             2
  1067 #define SQLITE_SET_LOCKPROXYFILE             3
  1068 #define SQLITE_LAST_ERRNO                    4
  1069 #define SQLITE_FCNTL_SIZE_HINT               5
  1070 #define SQLITE_FCNTL_CHUNK_SIZE              6
  1071 #define SQLITE_FCNTL_FILE_POINTER            7
  1072 #define SQLITE_FCNTL_SYNC_OMITTED            8
  1073 #define SQLITE_FCNTL_WIN32_AV_RETRY          9
  1074 #define SQLITE_FCNTL_PERSIST_WAL            10
  1075 #define SQLITE_FCNTL_OVERWRITE              11
  1076 #define SQLITE_FCNTL_VFSNAME                12
  1077 #define SQLITE_FCNTL_POWERSAFE_OVERWRITE    13
  1078 #define SQLITE_FCNTL_PRAGMA                 14
  1079 #define SQLITE_FCNTL_BUSYHANDLER            15
  1080 #define SQLITE_FCNTL_TEMPFILENAME           16
  1081 #define SQLITE_FCNTL_MMAP_SIZE              18
  1082 #define SQLITE_FCNTL_TRACE                  19
  1083 #define SQLITE_FCNTL_HAS_MOVED              20
  1084 #define SQLITE_FCNTL_SYNC                   21
  1085 #define SQLITE_FCNTL_COMMIT_PHASETWO        22
  1086 #define SQLITE_FCNTL_WIN32_SET_HANDLE       23
  1087 
  1088 /*
  1089 ** CAPI3REF: Mutex Handle
  1090 **
  1091 ** The mutex module within SQLite defines [sqlite3_mutex] to be an
  1092 ** abstract type for a mutex object.  The SQLite core never looks
  1093 ** at the internal representation of an [sqlite3_mutex].  It only
  1094 ** deals with pointers to the [sqlite3_mutex] object.
  1095 **
  1096 ** Mutexes are created using [sqlite3_mutex_alloc()].
  1097 */
  1098 typedef struct sqlite3_mutex sqlite3_mutex;
  1099 
  1100 /*
  1101 ** CAPI3REF: OS Interface Object
  1102 **
  1103 ** An instance of the sqlite3_vfs object defines the interface between
  1104 ** the SQLite core and the underlying operating system.  The "vfs"
  1105 ** in the name of the object stands for "virtual file system".  See
  1106 ** the [VFS | VFS documentation] for further information.
  1107 **
  1108 ** The value of the iVersion field is initially 1 but may be larger in
  1109 ** future versions of SQLite.  Additional fields may be appended to this
  1110 ** object when the iVersion value is increased.  Note that the structure
  1111 ** of the sqlite3_vfs object changes in the transaction between
  1112 ** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
  1113 ** modified.
  1114 **
  1115 ** The szOsFile field is the size of the subclassed [sqlite3_file]
  1116 ** structure used by this VFS.  mxPathname is the maximum length of
  1117 ** a pathname in this VFS.
  1118 **
  1119 ** Registered sqlite3_vfs objects are kept on a linked list formed by
  1120 ** the pNext pointer.  The [sqlite3_vfs_register()]
  1121 ** and [sqlite3_vfs_unregister()] interfaces manage this list
  1122 ** in a thread-safe way.  The [sqlite3_vfs_find()] interface
  1123 ** searches the list.  Neither the application code nor the VFS
  1124 ** implementation should use the pNext pointer.
  1125 **
  1126 ** The pNext field is the only field in the sqlite3_vfs
  1127 ** structure that SQLite will ever modify.  SQLite will only access
  1128 ** or modify this field while holding a particular static mutex.
  1129 ** The application should never modify anything within the sqlite3_vfs
  1130 ** object once the object has been registered.
  1131 **
  1132 ** The zName field holds the name of the VFS module.  The name must
  1133 ** be unique across all VFS modules.
  1134 **
  1135 ** [[sqlite3_vfs.xOpen]]
  1136 ** ^SQLite guarantees that the zFilename parameter to xOpen
  1137 ** is either a NULL pointer or string obtained
  1138 ** from xFullPathname() with an optional suffix added.
  1139 ** ^If a suffix is added to the zFilename parameter, it will
  1140 ** consist of a single "-" character followed by no more than
  1141 ** 11 alphanumeric and/or "-" characters.
  1142 ** ^SQLite further guarantees that
  1143 ** the string will be valid and unchanged until xClose() is
  1144 ** called. Because of the previous sentence,
  1145 ** the [sqlite3_file] can safely store a pointer to the
  1146 ** filename if it needs to remember the filename for some reason.
  1147 ** If the zFilename parameter to xOpen is a NULL pointer then xOpen
  1148 ** must invent its own temporary name for the file.  ^Whenever the 
  1149 ** xFilename parameter is NULL it will also be the case that the
  1150 ** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
  1151 **
  1152 ** The flags argument to xOpen() includes all bits set in
  1153 ** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
  1154 ** or [sqlite3_open16()] is used, then flags includes at least
  1155 ** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 
  1156 ** If xOpen() opens a file read-only then it sets *pOutFlags to
  1157 ** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
  1158 **
  1159 ** ^(SQLite will also add one of the following flags to the xOpen()
  1160 ** call, depending on the object being opened:
  1161 **
  1162 ** <ul>
  1163 ** <li>  [SQLITE_OPEN_MAIN_DB]
  1164 ** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
  1165 ** <li>  [SQLITE_OPEN_TEMP_DB]
  1166 ** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
  1167 ** <li>  [SQLITE_OPEN_TRANSIENT_DB]
  1168 ** <li>  [SQLITE_OPEN_SUBJOURNAL]
  1169 ** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
  1170 ** <li>  [SQLITE_OPEN_WAL]
  1171 ** </ul>)^
  1172 **
  1173 ** The file I/O implementation can use the object type flags to
  1174 ** change the way it deals with files.  For example, an application
  1175 ** that does not care about crash recovery or rollback might make
  1176 ** the open of a journal file a no-op.  Writes to this journal would
  1177 ** also be no-ops, and any attempt to read the journal would return
  1178 ** SQLITE_IOERR.  Or the implementation might recognize that a database
  1179 ** file will be doing page-aligned sector reads and writes in a random
  1180 ** order and set up its I/O subsystem accordingly.
  1181 **
  1182 ** SQLite might also add one of the following flags to the xOpen method:
  1183 **
  1184 ** <ul>
  1185 ** <li> [SQLITE_OPEN_DELETEONCLOSE]
  1186 ** <li> [SQLITE_OPEN_EXCLUSIVE]
  1187 ** </ul>
  1188 **
  1189 ** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
  1190 ** deleted when it is closed.  ^The [SQLITE_OPEN_DELETEONCLOSE]
  1191 ** will be set for TEMP databases and their journals, transient
  1192 ** databases, and subjournals.
  1193 **
  1194 ** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
  1195 ** with the [SQLITE_OPEN_CREATE] flag, which are both directly
  1196 ** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
  1197 ** API.  The SQLITE_OPEN_EXCLUSIVE flag, when paired with the 
  1198 ** SQLITE_OPEN_CREATE, is used to indicate that file should always
  1199 ** be created, and that it is an error if it already exists.
  1200 ** It is <i>not</i> used to indicate the file should be opened 
  1201 ** for exclusive access.
  1202 **
  1203 ** ^At least szOsFile bytes of memory are allocated by SQLite
  1204 ** to hold the  [sqlite3_file] structure passed as the third
  1205 ** argument to xOpen.  The xOpen method does not have to
  1206 ** allocate the structure; it should just fill it in.  Note that
  1207 ** the xOpen method must set the sqlite3_file.pMethods to either
  1208 ** a valid [sqlite3_io_methods] object or to NULL.  xOpen must do
  1209 ** this even if the open fails.  SQLite expects that the sqlite3_file.pMethods
  1210 ** element will be valid after xOpen returns regardless of the success
  1211 ** or failure of the xOpen call.
  1212 **
  1213 ** [[sqlite3_vfs.xAccess]]
  1214 ** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
  1215 ** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
  1216 ** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
  1217 ** to test whether a file is at least readable.   The file can be a
  1218 ** directory.
  1219 **
  1220 ** ^SQLite will always allocate at least mxPathname+1 bytes for the
  1221 ** output buffer xFullPathname.  The exact size of the output buffer
  1222 ** is also passed as a parameter to both  methods. If the output buffer
  1223 ** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
  1224 ** handled as a fatal error by SQLite, vfs implementations should endeavor
  1225 ** to prevent this by setting mxPathname to a sufficiently large value.
  1226 **
  1227 ** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
  1228 ** interfaces are not strictly a part of the filesystem, but they are
  1229 ** included in the VFS structure for completeness.
  1230 ** The xRandomness() function attempts to return nBytes bytes
  1231 ** of good-quality randomness into zOut.  The return value is
  1232 ** the actual number of bytes of randomness obtained.
  1233 ** The xSleep() method causes the calling thread to sleep for at
  1234 ** least the number of microseconds given.  ^The xCurrentTime()
  1235 ** method returns a Julian Day Number for the current date and time as
  1236 ** a floating point value.
  1237 ** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
  1238 ** Day Number multiplied by 86400000 (the number of milliseconds in 
  1239 ** a 24-hour day).  
  1240 ** ^SQLite will use the xCurrentTimeInt64() method to get the current
  1241 ** date and time if that method is available (if iVersion is 2 or 
  1242 ** greater and the function pointer is not NULL) and will fall back
  1243 ** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
  1244 **
  1245 ** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
  1246 ** are not used by the SQLite core.  These optional interfaces are provided
  1247 ** by some VFSes to facilitate testing of the VFS code. By overriding 
  1248 ** system calls with functions under its control, a test program can
  1249 ** simulate faults and error conditions that would otherwise be difficult
  1250 ** or impossible to induce.  The set of system calls that can be overridden
  1251 ** varies from one VFS to another, and from one version of the same VFS to the
  1252 ** next.  Applications that use these interfaces must be prepared for any
  1253 ** or all of these interfaces to be NULL or for their behavior to change
  1254 ** from one release to the next.  Applications must not attempt to access
  1255 ** any of these methods if the iVersion of the VFS is less than 3.
  1256 */
  1257 typedef struct sqlite3_vfs sqlite3_vfs;
  1258 typedef void (*sqlite3_syscall_ptr)(void);
  1259 struct sqlite3_vfs {
  1260   int iVersion;            /* Structure version number (currently 3) */
  1261   int szOsFile;            /* Size of subclassed sqlite3_file */
  1262   int mxPathname;          /* Maximum file pathname length */
  1263   sqlite3_vfs *pNext;      /* Next registered VFS */
  1264   const char *zName;       /* Name of this virtual file system */
  1265   void *pAppData;          /* Pointer to application-specific data */
  1266   int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
  1267                int flags, int *pOutFlags);
  1268   int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
  1269   int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
  1270   int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
  1271   void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
  1272   void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
  1273   void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
  1274   void (*xDlClose)(sqlite3_vfs*, void*);
  1275   int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
  1276   int (*xSleep)(sqlite3_vfs*, int microseconds);
  1277   int (*xCurrentTime)(sqlite3_vfs*, double*);
  1278   int (*xGetLastError)(sqlite3_vfs*, int, char *);
  1279   /*
  1280   ** The methods above are in version 1 of the sqlite_vfs object
  1281   ** definition.  Those that follow are added in version 2 or later
  1282   */
  1283   int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
  1284   /*
  1285   ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
  1286   ** Those below are for version 3 and greater.
  1287   */
  1288   int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
  1289   sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
  1290   const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
  1291   /*
  1292   ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
  1293   ** New fields may be appended in figure versions.  The iVersion
  1294   ** value will increment whenever this happens. 
  1295   */
  1296 };
  1297 
  1298 /*
  1299 ** CAPI3REF: Flags for the xAccess VFS method
  1300 **
  1301 ** These integer constants can be used as the third parameter to
  1302 ** the xAccess method of an [sqlite3_vfs] object.  They determine
  1303 ** what kind of permissions the xAccess method is looking for.
  1304 ** With SQLITE_ACCESS_EXISTS, the xAccess method
  1305 ** simply checks whether the file exists.
  1306 ** With SQLITE_ACCESS_READWRITE, the xAccess method
  1307 ** checks whether the named directory is both readable and writable
  1308 ** (in other words, if files can be added, removed, and renamed within
  1309 ** the directory).
  1310 ** The SQLITE_ACCESS_READWRITE constant is currently used only by the
  1311 ** [temp_store_directory pragma], though this could change in a future
  1312 ** release of SQLite.
  1313 ** With SQLITE_ACCESS_READ, the xAccess method
  1314 ** checks whether the file is readable.  The SQLITE_ACCESS_READ constant is
  1315 ** currently unused, though it might be used in a future release of
  1316 ** SQLite.
  1317 */
  1318 #define SQLITE_ACCESS_EXISTS    0
  1319 #define SQLITE_ACCESS_READWRITE 1   /* Used by PRAGMA temp_store_directory */
  1320 #define SQLITE_ACCESS_READ      2   /* Unused */
  1321 
  1322 /*
  1323 ** CAPI3REF: Flags for the xShmLock VFS method
  1324 **
  1325 ** These integer constants define the various locking operations
  1326 ** allowed by the xShmLock method of [sqlite3_io_methods].  The
  1327 ** following are the only legal combinations of flags to the
  1328 ** xShmLock method:
  1329 **
  1330 ** <ul>
  1331 ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
  1332 ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
  1333 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
  1334 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
  1335 ** </ul>
  1336 **
  1337 ** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
  1338 ** was given no the corresponding lock.  
  1339 **
  1340 ** The xShmLock method can transition between unlocked and SHARED or
  1341 ** between unlocked and EXCLUSIVE.  It cannot transition between SHARED
  1342 ** and EXCLUSIVE.
  1343 */
  1344 #define SQLITE_SHM_UNLOCK       1
  1345 #define SQLITE_SHM_LOCK         2
  1346 #define SQLITE_SHM_SHARED       4
  1347 #define SQLITE_SHM_EXCLUSIVE    8
  1348 
  1349 /*
  1350 ** CAPI3REF: Maximum xShmLock index
  1351 **
  1352 ** The xShmLock method on [sqlite3_io_methods] may use values
  1353 ** between 0 and this upper bound as its "offset" argument.
  1354 ** The SQLite core will never attempt to acquire or release a
  1355 ** lock outside of this range
  1356 */
  1357 #define SQLITE_SHM_NLOCK        8
  1358 
  1359 
  1360 /*
  1361 ** CAPI3REF: Initialize The SQLite Library
  1362 **
  1363 ** ^The sqlite3_initialize() routine initializes the
  1364 ** SQLite library.  ^The sqlite3_shutdown() routine
  1365 ** deallocates any resources that were allocated by sqlite3_initialize().
  1366 ** These routines are designed to aid in process initialization and
  1367 ** shutdown on embedded systems.  Workstation applications using
  1368 ** SQLite normally do not need to invoke either of these routines.
  1369 **
  1370 ** A call to sqlite3_initialize() is an "effective" call if it is
  1371 ** the first time sqlite3_initialize() is invoked during the lifetime of
  1372 ** the process, or if it is the first time sqlite3_initialize() is invoked
  1373 ** following a call to sqlite3_shutdown().  ^(Only an effective call
  1374 ** of sqlite3_initialize() does any initialization.  All other calls
  1375 ** are harmless no-ops.)^
  1376 **
  1377 ** A call to sqlite3_shutdown() is an "effective" call if it is the first
  1378 ** call to sqlite3_shutdown() since the last sqlite3_initialize().  ^(Only
  1379 ** an effective call to sqlite3_shutdown() does any deinitialization.
  1380 ** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
  1381 **
  1382 ** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
  1383 ** is not.  The sqlite3_shutdown() interface must only be called from a
  1384 ** single thread.  All open [database connections] must be closed and all
  1385 ** other SQLite resources must be deallocated prior to invoking
  1386 ** sqlite3_shutdown().
  1387 **
  1388 ** Among other things, ^sqlite3_initialize() will invoke
  1389 ** sqlite3_os_init().  Similarly, ^sqlite3_shutdown()
  1390 ** will invoke sqlite3_os_end().
  1391 **
  1392 ** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
  1393 ** ^If for some reason, sqlite3_initialize() is unable to initialize
  1394 ** the library (perhaps it is unable to allocate a needed resource such
  1395 ** as a mutex) it returns an [error code] other than [SQLITE_OK].
  1396 **
  1397 ** ^The sqlite3_initialize() routine is called internally by many other
  1398 ** SQLite interfaces so that an application usually does not need to
  1399 ** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
  1400 ** calls sqlite3_initialize() so the SQLite library will be automatically
  1401 ** initialized when [sqlite3_open()] is called if it has not be initialized
  1402 ** already.  ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
  1403 ** compile-time option, then the automatic calls to sqlite3_initialize()
  1404 ** are omitted and the application must call sqlite3_initialize() directly
  1405 ** prior to using any other SQLite interface.  For maximum portability,
  1406 ** it is recommended that applications always invoke sqlite3_initialize()
  1407 ** directly prior to using any other SQLite interface.  Future releases
  1408 ** of SQLite may require this.  In other words, the behavior exhibited
  1409 ** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
  1410 ** default behavior in some future release of SQLite.
  1411 **
  1412 ** The sqlite3_os_init() routine does operating-system specific
  1413 ** initialization of the SQLite library.  The sqlite3_os_end()
  1414 ** routine undoes the effect of sqlite3_os_init().  Typical tasks
  1415 ** performed by these routines include allocation or deallocation
  1416 ** of static resources, initialization of global variables,
  1417 ** setting up a default [sqlite3_vfs] module, or setting up
  1418 ** a default configuration using [sqlite3_config()].
  1419 **
  1420 ** The application should never invoke either sqlite3_os_init()
  1421 ** or sqlite3_os_end() directly.  The application should only invoke
  1422 ** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
  1423 ** interface is called automatically by sqlite3_initialize() and
  1424 ** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
  1425 ** implementations for sqlite3_os_init() and sqlite3_os_end()
  1426 ** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
  1427 ** When [custom builds | built for other platforms]
  1428 ** (using the [SQLITE_OS_OTHER=1] compile-time
  1429 ** option) the application must supply a suitable implementation for
  1430 ** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
  1431 ** implementation of sqlite3_os_init() or sqlite3_os_end()
  1432 ** must return [SQLITE_OK] on success and some other [error code] upon
  1433 ** failure.
  1434 */
  1435 SQLITE_API int sqlite3_initialize(void);
  1436 SQLITE_API int sqlite3_shutdown(void);
  1437 SQLITE_API int sqlite3_os_init(void);
  1438 SQLITE_API int sqlite3_os_end(void);
  1439 
  1440 /*
  1441 ** CAPI3REF: Configuring The SQLite Library
  1442 **
  1443 ** The sqlite3_config() interface is used to make global configuration
  1444 ** changes to SQLite in order to tune SQLite to the specific needs of
  1445 ** the application.  The default configuration is recommended for most
  1446 ** applications and so this routine is usually not necessary.  It is
  1447 ** provided to support rare applications with unusual needs.
  1448 **
  1449 ** The sqlite3_config() interface is not threadsafe.  The application
  1450 ** must insure that no other SQLite interfaces are invoked by other
  1451 ** threads while sqlite3_config() is running.  Furthermore, sqlite3_config()
  1452 ** may only be invoked prior to library initialization using
  1453 ** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
  1454 ** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
  1455 ** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
  1456 ** Note, however, that ^sqlite3_config() can be called as part of the
  1457 ** implementation of an application-defined [sqlite3_os_init()].
  1458 **
  1459 ** The first argument to sqlite3_config() is an integer
  1460 ** [configuration option] that determines
  1461 ** what property of SQLite is to be configured.  Subsequent arguments
  1462 ** vary depending on the [configuration option]
  1463 ** in the first argument.
  1464 **
  1465 ** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
  1466 ** ^If the option is unknown or SQLite is unable to set the option
  1467 ** then this routine returns a non-zero [error code].
  1468 */
  1469 SQLITE_API int sqlite3_config(int, ...);
  1470 
  1471 /*
  1472 ** CAPI3REF: Configure database connections
  1473 **
  1474 ** The sqlite3_db_config() interface is used to make configuration
  1475 ** changes to a [database connection].  The interface is similar to
  1476 ** [sqlite3_config()] except that the changes apply to a single
  1477 ** [database connection] (specified in the first argument).
  1478 **
  1479 ** The second argument to sqlite3_db_config(D,V,...)  is the
  1480 ** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
  1481 ** that indicates what aspect of the [database connection] is being configured.
  1482 ** Subsequent arguments vary depending on the configuration verb.
  1483 **
  1484 ** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
  1485 ** the call is considered successful.
  1486 */
  1487 SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
  1488 
  1489 /*
  1490 ** CAPI3REF: Memory Allocation Routines
  1491 **
  1492 ** An instance of this object defines the interface between SQLite
  1493 ** and low-level memory allocation routines.
  1494 **
  1495 ** This object is used in only one place in the SQLite interface.
  1496 ** A pointer to an instance of this object is the argument to
  1497 ** [sqlite3_config()] when the configuration option is
  1498 ** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].  
  1499 ** By creating an instance of this object
  1500 ** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
  1501 ** during configuration, an application can specify an alternative
  1502 ** memory allocation subsystem for SQLite to use for all of its
  1503 ** dynamic memory needs.
  1504 **
  1505 ** Note that SQLite comes with several [built-in memory allocators]
  1506 ** that are perfectly adequate for the overwhelming majority of applications
  1507 ** and that this object is only useful to a tiny minority of applications
  1508 ** with specialized memory allocation requirements.  This object is
  1509 ** also used during testing of SQLite in order to specify an alternative
  1510 ** memory allocator that simulates memory out-of-memory conditions in
  1511 ** order to verify that SQLite recovers gracefully from such
  1512 ** conditions.
  1513 **
  1514 ** The xMalloc, xRealloc, and xFree methods must work like the
  1515 ** malloc(), realloc() and free() functions from the standard C library.
  1516 ** ^SQLite guarantees that the second argument to
  1517 ** xRealloc is always a value returned by a prior call to xRoundup.
  1518 **
  1519 ** xSize should return the allocated size of a memory allocation
  1520 ** previously obtained from xMalloc or xRealloc.  The allocated size
  1521 ** is always at least as big as the requested size but may be larger.
  1522 **
  1523 ** The xRoundup method returns what would be the allocated size of
  1524 ** a memory allocation given a particular requested size.  Most memory
  1525 ** allocators round up memory allocations at least to the next multiple
  1526 ** of 8.  Some allocators round up to a larger multiple or to a power of 2.
  1527 ** Every memory allocation request coming in through [sqlite3_malloc()]
  1528 ** or [sqlite3_realloc()] first calls xRoundup.  If xRoundup returns 0, 
  1529 ** that causes the corresponding memory allocation to fail.
  1530 **
  1531 ** The xInit method initializes the memory allocator.  For example,
  1532 ** it might allocate any require mutexes or initialize internal data
  1533 ** structures.  The xShutdown method is invoked (indirectly) by
  1534 ** [sqlite3_shutdown()] and should deallocate any resources acquired
  1535 ** by xInit.  The pAppData pointer is used as the only parameter to
  1536 ** xInit and xShutdown.
  1537 **
  1538 ** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
  1539 ** the xInit method, so the xInit method need not be threadsafe.  The
  1540 ** xShutdown method is only called from [sqlite3_shutdown()] so it does
  1541 ** not need to be threadsafe either.  For all other methods, SQLite
  1542 ** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
  1543 ** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
  1544 ** it is by default) and so the methods are automatically serialized.
  1545 ** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
  1546 ** methods must be threadsafe or else make their own arrangements for
  1547 ** serialization.
  1548 **
  1549 ** SQLite will never invoke xInit() more than once without an intervening
  1550 ** call to xShutdown().
  1551 */
  1552 typedef struct sqlite3_mem_methods sqlite3_mem_methods;
  1553 struct sqlite3_mem_methods {
  1554   void *(*xMalloc)(int);         /* Memory allocation function */
  1555   void (*xFree)(void*);          /* Free a prior allocation */
  1556   void *(*xRealloc)(void*,int);  /* Resize an allocation */
  1557   int (*xSize)(void*);           /* Return the size of an allocation */
  1558   int (*xRoundup)(int);          /* Round up request size to allocation size */
  1559   int (*xInit)(void*);           /* Initialize the memory allocator */
  1560   void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  1561   void *pAppData;                /* Argument to xInit() and xShutdown() */
  1562 };
  1563 
  1564 /*
  1565 ** CAPI3REF: Configuration Options
  1566 ** KEYWORDS: {configuration option}
  1567 **
  1568 ** These constants are the available integer configuration options that
  1569 ** can be passed as the first argument to the [sqlite3_config()] interface.
  1570 **
  1571 ** New configuration options may be added in future releases of SQLite.
  1572 ** Existing configuration options might be discontinued.  Applications
  1573 ** should check the return code from [sqlite3_config()] to make sure that
  1574 ** the call worked.  The [sqlite3_config()] interface will return a
  1575 ** non-zero [error code] if a discontinued or unsupported configuration option
  1576 ** is invoked.
  1577 **
  1578 ** <dl>
  1579 ** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
  1580 ** <dd>There are no arguments to this option.  ^This option sets the
  1581 ** [threading mode] to Single-thread.  In other words, it disables
  1582 ** all mutexing and puts SQLite into a mode where it can only be used
  1583 ** by a single thread.   ^If SQLite is compiled with
  1584 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1585 ** it is not possible to change the [threading mode] from its default
  1586 ** value of Single-thread and so [sqlite3_config()] will return 
  1587 ** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
  1588 ** configuration option.</dd>
  1589 **
  1590 ** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>
  1591 ** <dd>There are no arguments to this option.  ^This option sets the
  1592 ** [threading mode] to Multi-thread.  In other words, it disables
  1593 ** mutexing on [database connection] and [prepared statement] objects.
  1594 ** The application is responsible for serializing access to
  1595 ** [database connections] and [prepared statements].  But other mutexes
  1596 ** are enabled so that SQLite will be safe to use in a multi-threaded
  1597 ** environment as long as no two threads attempt to use the same
  1598 ** [database connection] at the same time.  ^If SQLite is compiled with
  1599 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1600 ** it is not possible to set the Multi-thread [threading mode] and
  1601 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1602 ** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
  1603 **
  1604 ** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>
  1605 ** <dd>There are no arguments to this option.  ^This option sets the
  1606 ** [threading mode] to Serialized. In other words, this option enables
  1607 ** all mutexes including the recursive
  1608 ** mutexes on [database connection] and [prepared statement] objects.
  1609 ** In this mode (which is the default when SQLite is compiled with
  1610 ** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
  1611 ** to [database connections] and [prepared statements] so that the
  1612 ** application is free to use the same [database connection] or the
  1613 ** same [prepared statement] in different threads at the same time.
  1614 ** ^If SQLite is compiled with
  1615 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1616 ** it is not possible to set the Serialized [threading mode] and
  1617 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1618 ** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
  1619 **
  1620 ** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>
  1621 ** <dd> ^(This option takes a single argument which is a pointer to an
  1622 ** instance of the [sqlite3_mem_methods] structure.  The argument specifies
  1623 ** alternative low-level memory allocation routines to be used in place of
  1624 ** the memory allocation routines built into SQLite.)^ ^SQLite makes
  1625 ** its own private copy of the content of the [sqlite3_mem_methods] structure
  1626 ** before the [sqlite3_config()] call returns.</dd>
  1627 **
  1628 ** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>
  1629 ** <dd> ^(This option takes a single argument which is a pointer to an
  1630 ** instance of the [sqlite3_mem_methods] structure.  The [sqlite3_mem_methods]
  1631 ** structure is filled with the currently defined memory allocation routines.)^
  1632 ** This option can be used to overload the default memory allocation
  1633 ** routines with a wrapper that simulations memory allocation failure or
  1634 ** tracks memory usage, for example. </dd>
  1635 **
  1636 ** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
  1637 ** <dd> ^This option takes single argument of type int, interpreted as a 
  1638 ** boolean, which enables or disables the collection of memory allocation 
  1639 ** statistics. ^(When memory allocation statistics are disabled, the 
  1640 ** following SQLite interfaces become non-operational:
  1641 **   <ul>
  1642 **   <li> [sqlite3_memory_used()]
  1643 **   <li> [sqlite3_memory_highwater()]
  1644 **   <li> [sqlite3_soft_heap_limit64()]
  1645 **   <li> [sqlite3_status()]
  1646 **   </ul>)^
  1647 ** ^Memory allocation statistics are enabled by default unless SQLite is
  1648 ** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
  1649 ** allocation statistics are disabled by default.
  1650 ** </dd>
  1651 **
  1652 ** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
  1653 ** <dd> ^This option specifies a static memory buffer that SQLite can use for
  1654 ** scratch memory.  There are three arguments:  A pointer an 8-byte
  1655 ** aligned memory buffer from which the scratch allocations will be
  1656 ** drawn, the size of each scratch allocation (sz),
  1657 ** and the maximum number of scratch allocations (N).  The sz
  1658 ** argument must be a multiple of 16.
  1659 ** The first argument must be a pointer to an 8-byte aligned buffer
  1660 ** of at least sz*N bytes of memory.
  1661 ** ^SQLite will use no more than two scratch buffers per thread.  So
  1662 ** N should be set to twice the expected maximum number of threads.
  1663 ** ^SQLite will never require a scratch buffer that is more than 6
  1664 ** times the database page size. ^If SQLite needs needs additional
  1665 ** scratch memory beyond what is provided by this configuration option, then 
  1666 ** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
  1667 **
  1668 ** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
  1669 ** <dd> ^This option specifies a static memory buffer that SQLite can use for
  1670 ** the database page cache with the default page cache implementation.  
  1671 ** This configuration should not be used if an application-define page
  1672 ** cache implementation is loaded using the SQLITE_CONFIG_PCACHE2 option.
  1673 ** There are three arguments to this option: A pointer to 8-byte aligned
  1674 ** memory, the size of each page buffer (sz), and the number of pages (N).
  1675 ** The sz argument should be the size of the largest database page
  1676 ** (a power of two between 512 and 32768) plus a little extra for each
  1677 ** page header.  ^The page header size is 20 to 40 bytes depending on
  1678 ** the host architecture.  ^It is harmless, apart from the wasted memory,
  1679 ** to make sz a little too large.  The first
  1680 ** argument should point to an allocation of at least sz*N bytes of memory.
  1681 ** ^SQLite will use the memory provided by the first argument to satisfy its
  1682 ** memory needs for the first N pages that it adds to cache.  ^If additional
  1683 ** page cache memory is needed beyond what is provided by this option, then
  1684 ** SQLite goes to [sqlite3_malloc()] for the additional storage space.
  1685 ** The pointer in the first argument must
  1686 ** be aligned to an 8-byte boundary or subsequent behavior of SQLite
  1687 ** will be undefined.</dd>
  1688 **
  1689 ** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
  1690 ** <dd> ^This option specifies a static memory buffer that SQLite will use
  1691 ** for all of its dynamic memory allocation needs beyond those provided
  1692 ** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
  1693 ** There are three arguments: An 8-byte aligned pointer to the memory,
  1694 ** the number of bytes in the memory buffer, and the minimum allocation size.
  1695 ** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
  1696 ** to using its default memory allocator (the system malloc() implementation),
  1697 ** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
  1698 ** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
  1699 ** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
  1700 ** allocator is engaged to handle all of SQLites memory allocation needs.
  1701 ** The first pointer (the memory pointer) must be aligned to an 8-byte
  1702 ** boundary or subsequent behavior of SQLite will be undefined.
  1703 ** The minimum allocation size is capped at 2**12. Reasonable values
  1704 ** for the minimum allocation size are 2**5 through 2**8.</dd>
  1705 **
  1706 ** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
  1707 ** <dd> ^(This option takes a single argument which is a pointer to an
  1708 ** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
  1709 ** alternative low-level mutex routines to be used in place
  1710 ** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
  1711 ** content of the [sqlite3_mutex_methods] structure before the call to
  1712 ** [sqlite3_config()] returns. ^If SQLite is compiled with
  1713 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1714 ** the entire mutexing subsystem is omitted from the build and hence calls to
  1715 ** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
  1716 ** return [SQLITE_ERROR].</dd>
  1717 **
  1718 ** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>
  1719 ** <dd> ^(This option takes a single argument which is a pointer to an
  1720 ** instance of the [sqlite3_mutex_methods] structure.  The
  1721 ** [sqlite3_mutex_methods]
  1722 ** structure is filled with the currently defined mutex routines.)^
  1723 ** This option can be used to overload the default mutex allocation
  1724 ** routines with a wrapper used to track mutex usage for performance
  1725 ** profiling or testing, for example.   ^If SQLite is compiled with
  1726 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1727 ** the entire mutexing subsystem is omitted from the build and hence calls to
  1728 ** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
  1729 ** return [SQLITE_ERROR].</dd>
  1730 **
  1731 ** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>
  1732 ** <dd> ^(This option takes two arguments that determine the default
  1733 ** memory allocation for the lookaside memory allocator on each
  1734 ** [database connection].  The first argument is the
  1735 ** size of each lookaside buffer slot and the second is the number of
  1736 ** slots allocated to each database connection.)^  ^(This option sets the
  1737 ** <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
  1738 ** verb to [sqlite3_db_config()] can be used to change the lookaside
  1739 ** configuration on individual connections.)^ </dd>
  1740 **
  1741 ** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>
  1742 ** <dd> ^(This option takes a single argument which is a pointer to
  1743 ** an [sqlite3_pcache_methods2] object.  This object specifies the interface
  1744 ** to a custom page cache implementation.)^  ^SQLite makes a copy of the
  1745 ** object and uses it for page cache memory allocations.</dd>
  1746 **
  1747 ** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
  1748 ** <dd> ^(This option takes a single argument which is a pointer to an
  1749 ** [sqlite3_pcache_methods2] object.  SQLite copies of the current
  1750 ** page cache implementation into that object.)^ </dd>
  1751 **
  1752 ** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
  1753 ** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
  1754 ** global [error log].
  1755 ** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
  1756 ** function with a call signature of void(*)(void*,int,const char*), 
  1757 ** and a pointer to void. ^If the function pointer is not NULL, it is
  1758 ** invoked by [sqlite3_log()] to process each logging event.  ^If the
  1759 ** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
  1760 ** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
  1761 ** passed through as the first parameter to the application-defined logger
  1762 ** function whenever that function is invoked.  ^The second parameter to
  1763 ** the logger function is a copy of the first parameter to the corresponding
  1764 ** [sqlite3_log()] call and is intended to be a [result code] or an
  1765 ** [extended result code].  ^The third parameter passed to the logger is
  1766 ** log message after formatting via [sqlite3_snprintf()].
  1767 ** The SQLite logging interface is not reentrant; the logger function
  1768 ** supplied by the application must not invoke any SQLite interface.
  1769 ** In a multi-threaded application, the application-defined logger
  1770 ** function must be threadsafe. </dd>
  1771 **
  1772 ** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
  1773 ** <dd>^(This option takes a single argument of type int. If non-zero, then
  1774 ** URI handling is globally enabled. If the parameter is zero, then URI handling
  1775 ** is globally disabled.)^ ^If URI handling is globally enabled, all filenames
  1776 ** passed to [sqlite3_open()], [sqlite3_open_v2()], [sqlite3_open16()] or
  1777 ** specified as part of [ATTACH] commands are interpreted as URIs, regardless
  1778 ** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
  1779 ** connection is opened. ^If it is globally disabled, filenames are
  1780 ** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
  1781 ** database connection is opened. ^(By default, URI handling is globally
  1782 ** disabled. The default value may be changed by compiling with the
  1783 ** [SQLITE_USE_URI] symbol defined.)^
  1784 **
  1785 ** [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN
  1786 ** <dd>^This option takes a single integer argument which is interpreted as
  1787 ** a boolean in order to enable or disable the use of covering indices for
  1788 ** full table scans in the query optimizer.  ^The default setting is determined
  1789 ** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
  1790 ** if that compile-time option is omitted.
  1791 ** The ability to disable the use of covering indices for full table scans
  1792 ** is because some incorrectly coded legacy applications might malfunction
  1793 ** when the optimization is enabled.  Providing the ability to
  1794 ** disable the optimization allows the older, buggy application code to work
  1795 ** without change even with newer versions of SQLite.
  1796 **
  1797 ** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
  1798 ** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE
  1799 ** <dd> These options are obsolete and should not be used by new code.
  1800 ** They are retained for backwards compatibility but are now no-ops.
  1801 ** </dd>
  1802 **
  1803 ** [[SQLITE_CONFIG_SQLLOG]]
  1804 ** <dt>SQLITE_CONFIG_SQLLOG
  1805 ** <dd>This option is only available if sqlite is compiled with the
  1806 ** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
  1807 ** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
  1808 ** The second should be of type (void*). The callback is invoked by the library
  1809 ** in three separate circumstances, identified by the value passed as the
  1810 ** fourth parameter. If the fourth parameter is 0, then the database connection
  1811 ** passed as the second argument has just been opened. The third argument
  1812 ** points to a buffer containing the name of the main database file. If the
  1813 ** fourth parameter is 1, then the SQL statement that the third parameter
  1814 ** points to has just been executed. Or, if the fourth parameter is 2, then
  1815 ** the connection being passed as the second parameter is being closed. The
  1816 ** third parameter is passed NULL In this case.  An example of using this
  1817 ** configuration option can be seen in the "test_sqllog.c" source file in
  1818 ** the canonical SQLite source tree.</dd>
  1819 **
  1820 ** [[SQLITE_CONFIG_MMAP_SIZE]]
  1821 ** <dt>SQLITE_CONFIG_MMAP_SIZE
  1822 ** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
  1823 ** that are the default mmap size limit (the default setting for
  1824 ** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
  1825 ** ^The default setting can be overridden by each database connection using
  1826 ** either the [PRAGMA mmap_size] command, or by using the
  1827 ** [SQLITE_FCNTL_MMAP_SIZE] file control.  ^(The maximum allowed mmap size
  1828 ** cannot be changed at run-time.  Nor may the maximum allowed mmap size
  1829 ** exceed the compile-time maximum mmap size set by the
  1830 ** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^
  1831 ** ^If either argument to this option is negative, then that argument is
  1832 ** changed to its compile-time default.
  1833 **
  1834 ** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]
  1835 ** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE
  1836 ** <dd>^This option is only available if SQLite is compiled for Windows
  1837 ** with the [SQLITE_WIN32_MALLOC] pre-processor macro defined.
  1838 ** SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
  1839 ** that specifies the maximum size of the created heap.
  1840 ** </dl>
  1841 */
  1842 #define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
  1843 #define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
  1844 #define SQLITE_CONFIG_SERIALIZED    3  /* nil */
  1845 #define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
  1846 #define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
  1847 #define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
  1848 #define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
  1849 #define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
  1850 #define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
  1851 #define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
  1852 #define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
  1853 /* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
  1854 #define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
  1855 #define SQLITE_CONFIG_PCACHE       14  /* no-op */
  1856 #define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
  1857 #define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
  1858 #define SQLITE_CONFIG_URI          17  /* int */
  1859 #define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
  1860 #define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
  1861 #define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
  1862 #define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
  1863 #define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */
  1864 #define SQLITE_CONFIG_WIN32_HEAPSIZE      23  /* int nByte */
  1865 
  1866 /*
  1867 ** CAPI3REF: Database Connection Configuration Options
  1868 **
  1869 ** These constants are the available integer configuration options that
  1870 ** can be passed as the second argument to the [sqlite3_db_config()] interface.
  1871 **
  1872 ** New configuration options may be added in future releases of SQLite.
  1873 ** Existing configuration options might be discontinued.  Applications
  1874 ** should check the return code from [sqlite3_db_config()] to make sure that
  1875 ** the call worked.  ^The [sqlite3_db_config()] interface will return a
  1876 ** non-zero [error code] if a discontinued or unsupported configuration option
  1877 ** is invoked.
  1878 **
  1879 ** <dl>
  1880 ** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
  1881 ** <dd> ^This option takes three additional arguments that determine the 
  1882 ** [lookaside memory allocator] configuration for the [database connection].
  1883 ** ^The first argument (the third parameter to [sqlite3_db_config()] is a
  1884 ** pointer to a memory buffer to use for lookaside memory.
  1885 ** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
  1886 ** may be NULL in which case SQLite will allocate the
  1887 ** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
  1888 ** size of each lookaside buffer slot.  ^The third argument is the number of
  1889 ** slots.  The size of the buffer in the first argument must be greater than
  1890 ** or equal to the product of the second and third arguments.  The buffer
  1891 ** must be aligned to an 8-byte boundary.  ^If the second argument to
  1892 ** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
  1893 ** rounded down to the next smaller multiple of 8.  ^(The lookaside memory
  1894 ** configuration for a database connection can only be changed when that
  1895 ** connection is not currently using lookaside memory, or in other words
  1896 ** when the "current value" returned by
  1897 ** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
  1898 ** Any attempt to change the lookaside memory configuration when lookaside
  1899 ** memory is in use leaves the configuration unchanged and returns 
  1900 ** [SQLITE_BUSY].)^</dd>
  1901 **
  1902 ** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
  1903 ** <dd> ^This option is used to enable or disable the enforcement of
  1904 ** [foreign key constraints].  There should be two additional arguments.
  1905 ** The first argument is an integer which is 0 to disable FK enforcement,
  1906 ** positive to enable FK enforcement or negative to leave FK enforcement
  1907 ** unchanged.  The second parameter is a pointer to an integer into which
  1908 ** is written 0 or 1 to indicate whether FK enforcement is off or on
  1909 ** following this call.  The second parameter may be a NULL pointer, in
  1910 ** which case the FK enforcement setting is not reported back. </dd>
  1911 **
  1912 ** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
  1913 ** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
  1914 ** There should be two additional arguments.
  1915 ** The first argument is an integer which is 0 to disable triggers,
  1916 ** positive to enable triggers or negative to leave the setting unchanged.
  1917 ** The second parameter is a pointer to an integer into which
  1918 ** is written 0 or 1 to indicate whether triggers are disabled or enabled
  1919 ** following this call.  The second parameter may be a NULL pointer, in
  1920 ** which case the trigger setting is not reported back. </dd>
  1921 **
  1922 ** </dl>
  1923 */
  1924 #define SQLITE_DBCONFIG_LOOKASIDE       1001  /* void* int int */
  1925 #define SQLITE_DBCONFIG_ENABLE_FKEY     1002  /* int int* */
  1926 #define SQLITE_DBCONFIG_ENABLE_TRIGGER  1003  /* int int* */
  1927 
  1928 
  1929 /*
  1930 ** CAPI3REF: Enable Or Disable Extended Result Codes
  1931 **
  1932 ** ^The sqlite3_extended_result_codes() routine enables or disables the
  1933 ** [extended result codes] feature of SQLite. ^The extended result
  1934 ** codes are disabled by default for historical compatibility.
  1935 */
  1936 SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);
  1937 
  1938 /*
  1939 ** CAPI3REF: Last Insert Rowid
  1940 **
  1941 ** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)
  1942 ** has a unique 64-bit signed
  1943 ** integer key called the [ROWID | "rowid"]. ^The rowid is always available
  1944 ** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
  1945 ** names are not also used by explicitly declared columns. ^If
  1946 ** the table has a column of type [INTEGER PRIMARY KEY] then that column
  1947 ** is another alias for the rowid.
  1948 **
  1949 ** ^The sqlite3_last_insert_rowid(D) interface returns the [rowid] of the 
  1950 ** most recent successful [INSERT] into a rowid table or [virtual table]
  1951 ** on database connection D.
  1952 ** ^Inserts into [WITHOUT ROWID] tables are not recorded.
  1953 ** ^If no successful [INSERT]s into rowid tables
  1954 ** have ever occurred on the database connection D, 
  1955 ** then sqlite3_last_insert_rowid(D) returns zero.
  1956 **
  1957 ** ^(If an [INSERT] occurs within a trigger or within a [virtual table]
  1958 ** method, then this routine will return the [rowid] of the inserted
  1959 ** row as long as the trigger or virtual table method is running.
  1960 ** But once the trigger or virtual table method ends, the value returned 
  1961 ** by this routine reverts to what it was before the trigger or virtual
  1962 ** table method began.)^
  1963 **
  1964 ** ^An [INSERT] that fails due to a constraint violation is not a
  1965 ** successful [INSERT] and does not change the value returned by this
  1966 ** routine.  ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
  1967 ** and INSERT OR ABORT make no changes to the return value of this
  1968 ** routine when their insertion fails.  ^(When INSERT OR REPLACE
  1969 ** encounters a constraint violation, it does not fail.  The
  1970 ** INSERT continues to completion after deleting rows that caused
  1971 ** the constraint problem so INSERT OR REPLACE will always change
  1972 ** the return value of this interface.)^
  1973 **
  1974 ** ^For the purposes of this routine, an [INSERT] is considered to
  1975 ** be successful even if it is subsequently rolled back.
  1976 **
  1977 ** This function is accessible to SQL statements via the
  1978 ** [last_insert_rowid() SQL function].
  1979 **
  1980 ** If a separate thread performs a new [INSERT] on the same
  1981 ** database connection while the [sqlite3_last_insert_rowid()]
  1982 ** function is running and thus changes the last insert [rowid],
  1983 ** then the value returned by [sqlite3_last_insert_rowid()] is
  1984 ** unpredictable and might not equal either the old or the new
  1985 ** last insert [rowid].
  1986 */
  1987 SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
  1988 
  1989 /*
  1990 ** CAPI3REF: Count The Number Of Rows Modified
  1991 **
  1992 ** ^This function returns the number of database rows that were changed
  1993 ** or inserted or deleted by the most recently completed SQL statement
  1994 ** on the [database connection] specified by the first parameter.
  1995 ** ^(Only changes that are directly specified by the [INSERT], [UPDATE],
  1996 ** or [DELETE] statement are counted.  Auxiliary changes caused by
  1997 ** triggers or [foreign key actions] are not counted.)^ Use the
  1998 ** [sqlite3_total_changes()] function to find the total number of changes
  1999 ** including changes caused by triggers and foreign key actions.
  2000 **
  2001 ** ^Changes to a view that are simulated by an [INSTEAD OF trigger]
  2002 ** are not counted.  Only real table changes are counted.
  2003 **
  2004 ** ^(A "row change" is a change to a single row of a single table
  2005 ** caused by an INSERT, DELETE, or UPDATE statement.  Rows that
  2006 ** are changed as side effects of [REPLACE] constraint resolution,
  2007 ** rollback, ABORT processing, [DROP TABLE], or by any other
  2008 ** mechanisms do not count as direct row changes.)^
  2009 **
  2010 ** A "trigger context" is a scope of execution that begins and
  2011 ** ends with the script of a [CREATE TRIGGER | trigger]. 
  2012 ** Most SQL statements are
  2013 ** evaluated outside of any trigger.  This is the "top level"
  2014 ** trigger context.  If a trigger fires from the top level, a
  2015 ** new trigger context is entered for the duration of that one
  2016 ** trigger.  Subtriggers create subcontexts for their duration.
  2017 **
  2018 ** ^Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
  2019 ** not create a new trigger context.
  2020 **
  2021 ** ^This function returns the number of direct row changes in the
  2022 ** most recent INSERT, UPDATE, or DELETE statement within the same
  2023 ** trigger context.
  2024 **
  2025 ** ^Thus, when called from the top level, this function returns the
  2026 ** number of changes in the most recent INSERT, UPDATE, or DELETE
  2027 ** that also occurred at the top level.  ^(Within the body of a trigger,
  2028 ** the sqlite3_changes() interface can be called to find the number of
  2029 ** changes in the most recently completed INSERT, UPDATE, or DELETE
  2030 ** statement within the body of the same trigger.
  2031 ** However, the number returned does not include changes
  2032 ** caused by subtriggers since those have their own context.)^
  2033 **
  2034 ** See also the [sqlite3_total_changes()] interface, the
  2035 ** [count_changes pragma], and the [changes() SQL function].
  2036 **
  2037 ** If a separate thread makes changes on the same database connection
  2038 ** while [sqlite3_changes()] is running then the value returned
  2039 ** is unpredictable and not meaningful.
  2040 */
  2041 SQLITE_API int sqlite3_changes(sqlite3*);
  2042 
  2043 /*
  2044 ** CAPI3REF: Total Number Of Rows Modified
  2045 **
  2046 ** ^This function returns the number of row changes caused by [INSERT],
  2047 ** [UPDATE] or [DELETE] statements since the [database connection] was opened.
  2048 ** ^(The count returned by sqlite3_total_changes() includes all changes
  2049 ** from all [CREATE TRIGGER | trigger] contexts and changes made by
  2050 ** [foreign key actions]. However,
  2051 ** the count does not include changes used to implement [REPLACE] constraints,
  2052 ** do rollbacks or ABORT processing, or [DROP TABLE] processing.  The
  2053 ** count does not include rows of views that fire an [INSTEAD OF trigger],
  2054 ** though if the INSTEAD OF trigger makes changes of its own, those changes 
  2055 ** are counted.)^
  2056 ** ^The sqlite3_total_changes() function counts the changes as soon as
  2057 ** the statement that makes them is completed (when the statement handle
  2058 ** is passed to [sqlite3_reset()] or [sqlite3_finalize()]).
  2059 **
  2060 ** See also the [sqlite3_changes()] interface, the
  2061 ** [count_changes pragma], and the [total_changes() SQL function].
  2062 **
  2063 ** If a separate thread makes changes on the same database connection
  2064 ** while [sqlite3_total_changes()] is running then the value
  2065 ** returned is unpredictable and not meaningful.
  2066 */
  2067 SQLITE_API int sqlite3_total_changes(sqlite3*);
  2068 
  2069 /*
  2070 ** CAPI3REF: Interrupt A Long-Running Query
  2071 **
  2072 ** ^This function causes any pending database operation to abort and
  2073 ** return at its earliest opportunity. This routine is typically
  2074 ** called in response to a user action such as pressing "Cancel"
  2075 ** or Ctrl-C where the user wants a long query operation to halt
  2076 ** immediately.
  2077 **
  2078 ** ^It is safe to call this routine from a thread different from the
  2079 ** thread that is currently running the database operation.  But it
  2080 ** is not safe to call this routine with a [database connection] that
  2081 ** is closed or might close before sqlite3_interrupt() returns.
  2082 **
  2083 ** ^If an SQL operation is very nearly finished at the time when
  2084 ** sqlite3_interrupt() is called, then it might not have an opportunity
  2085 ** to be interrupted and might continue to completion.
  2086 **
  2087 ** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
  2088 ** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
  2089 ** that is inside an explicit transaction, then the entire transaction
  2090 ** will be rolled back automatically.
  2091 **
  2092 ** ^The sqlite3_interrupt(D) call is in effect until all currently running
  2093 ** SQL statements on [database connection] D complete.  ^Any new SQL statements
  2094 ** that are started after the sqlite3_interrupt() call and before the 
  2095 ** running statements reaches zero are interrupted as if they had been
  2096 ** running prior to the sqlite3_interrupt() call.  ^New SQL statements
  2097 ** that are started after the running statement count reaches zero are
  2098 ** not effected by the sqlite3_interrupt().
  2099 ** ^A call to sqlite3_interrupt(D) that occurs when there are no running
  2100 ** SQL statements is a no-op and has no effect on SQL statements
  2101 ** that are started after the sqlite3_interrupt() call returns.
  2102 **
  2103 ** If the database connection closes while [sqlite3_interrupt()]
  2104 ** is running then bad things will likely happen.
  2105 */
  2106 SQLITE_API void sqlite3_interrupt(sqlite3*);
  2107 
  2108 /*
  2109 ** CAPI3REF: Determine If An SQL Statement Is Complete
  2110 **
  2111 ** These routines are useful during command-line input to determine if the
  2112 ** currently entered text seems to form a complete SQL statement or
  2113 ** if additional input is needed before sending the text into
  2114 ** SQLite for parsing.  ^These routines return 1 if the input string
  2115 ** appears to be a complete SQL statement.  ^A statement is judged to be
  2116 ** complete if it ends with a semicolon token and is not a prefix of a
  2117 ** well-formed CREATE TRIGGER statement.  ^Semicolons that are embedded within
  2118 ** string literals or quoted identifier names or comments are not
  2119 ** independent tokens (they are part of the token in which they are
  2120 ** embedded) and thus do not count as a statement terminator.  ^Whitespace
  2121 ** and comments that follow the final semicolon are ignored.
  2122 **
  2123 ** ^These routines return 0 if the statement is incomplete.  ^If a
  2124 ** memory allocation fails, then SQLITE_NOMEM is returned.
  2125 **
  2126 ** ^These routines do not parse the SQL statements thus
  2127 ** will not detect syntactically incorrect SQL.
  2128 **
  2129 ** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior 
  2130 ** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
  2131 ** automatically by sqlite3_complete16().  If that initialization fails,
  2132 ** then the return value from sqlite3_complete16() will be non-zero
  2133 ** regardless of whether or not the input SQL is complete.)^
  2134 **
  2135 ** The input to [sqlite3_complete()] must be a zero-terminated
  2136 ** UTF-8 string.
  2137 **
  2138 ** The input to [sqlite3_complete16()] must be a zero-terminated
  2139 ** UTF-16 string in native byte order.
  2140 */
  2141 SQLITE_API int sqlite3_complete(const char *sql);
  2142 SQLITE_API int sqlite3_complete16(const void *sql);
  2143 
  2144 /*
  2145 ** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
  2146 **
  2147 ** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X
  2148 ** that might be invoked with argument P whenever
  2149 ** an attempt is made to access a database table associated with
  2150 ** [database connection] D when another thread
  2151 ** or process has the table locked.
  2152 ** The sqlite3_busy_handler() interface is used to implement
  2153 ** [sqlite3_busy_timeout()] and [PRAGMA busy_timeout].
  2154 **
  2155 ** ^If the busy callback is NULL, then [SQLITE_BUSY]
  2156 ** is returned immediately upon encountering the lock.  ^If the busy callback
  2157 ** is not NULL, then the callback might be invoked with two arguments.
  2158 **
  2159 ** ^The first argument to the busy handler is a copy of the void* pointer which
  2160 ** is the third argument to sqlite3_busy_handler().  ^The second argument to
  2161 ** the busy handler callback is the number of times that the busy handler has
  2162 ** been invoked for the same locking event.  ^If the
  2163 ** busy callback returns 0, then no additional attempts are made to
  2164 ** access the database and [SQLITE_BUSY] is returned
  2165 ** to the application.
  2166 ** ^If the callback returns non-zero, then another attempt
  2167 ** is made to access the database and the cycle repeats.
  2168 **
  2169 ** The presence of a busy handler does not guarantee that it will be invoked
  2170 ** when there is lock contention. ^If SQLite determines that invoking the busy
  2171 ** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
  2172 ** to the application instead of invoking the 
  2173 ** busy handler.
  2174 ** Consider a scenario where one process is holding a read lock that
  2175 ** it is trying to promote to a reserved lock and
  2176 ** a second process is holding a reserved lock that it is trying
  2177 ** to promote to an exclusive lock.  The first process cannot proceed
  2178 ** because it is blocked by the second and the second process cannot
  2179 ** proceed because it is blocked by the first.  If both processes
  2180 ** invoke the busy handlers, neither will make any progress.  Therefore,
  2181 ** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
  2182 ** will induce the first process to release its read lock and allow
  2183 ** the second process to proceed.
  2184 **
  2185 ** ^The default busy callback is NULL.
  2186 **
  2187 ** ^(There can only be a single busy handler defined for each
  2188 ** [database connection].  Setting a new busy handler clears any
  2189 ** previously set handler.)^  ^Note that calling [sqlite3_busy_timeout()]
  2190 ** or evaluating [PRAGMA busy_timeout=N] will change the
  2191 ** busy handler and thus clear any previously set busy handler.
  2192 **
  2193 ** The busy callback should not take any actions which modify the
  2194 ** database connection that invoked the busy handler.  In other words,
  2195 ** the busy handler is not reentrant.  Any such actions
  2196 ** result in undefined behavior.
  2197 ** 
  2198 ** A busy handler must not close the database connection
  2199 ** or [prepared statement] that invoked the busy handler.
  2200 */
  2201 SQLITE_API int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);
  2202 
  2203 /*
  2204 ** CAPI3REF: Set A Busy Timeout
  2205 **
  2206 ** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
  2207 ** for a specified amount of time when a table is locked.  ^The handler
  2208 ** will sleep multiple times until at least "ms" milliseconds of sleeping
  2209 ** have accumulated.  ^After at least "ms" milliseconds of sleeping,
  2210 ** the handler returns 0 which causes [sqlite3_step()] to return
  2211 ** [SQLITE_BUSY].
  2212 **
  2213 ** ^Calling this routine with an argument less than or equal to zero
  2214 ** turns off all busy handlers.
  2215 **
  2216 ** ^(There can only be a single busy handler for a particular
  2217 ** [database connection] any any given moment.  If another busy handler
  2218 ** was defined  (using [sqlite3_busy_handler()]) prior to calling
  2219 ** this routine, that other busy handler is cleared.)^
  2220 **
  2221 ** See also:  [PRAGMA busy_timeout]
  2222 */
  2223 SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
  2224 
  2225 /*
  2226 ** CAPI3REF: Convenience Routines For Running Queries
  2227 **
  2228 ** This is a legacy interface that is preserved for backwards compatibility.
  2229 ** Use of this interface is not recommended.
  2230 **
  2231 ** Definition: A <b>result table</b> is memory data structure created by the
  2232 ** [sqlite3_get_table()] interface.  A result table records the
  2233 ** complete query results from one or more queries.
  2234 **
  2235 ** The table conceptually has a number of rows and columns.  But
  2236 ** these numbers are not part of the result table itself.  These
  2237 ** numbers are obtained separately.  Let N be the number of rows
  2238 ** and M be the number of columns.
  2239 **
  2240 ** A result table is an array of pointers to zero-terminated UTF-8 strings.
  2241 ** There are (N+1)*M elements in the array.  The first M pointers point
  2242 ** to zero-terminated strings that  contain the names of the columns.
  2243 ** The remaining entries all point to query results.  NULL values result
  2244 ** in NULL pointers.  All other values are in their UTF-8 zero-terminated
  2245 ** string representation as returned by [sqlite3_column_text()].
  2246 **
  2247 ** A result table might consist of one or more memory allocations.
  2248 ** It is not safe to pass a result table directly to [sqlite3_free()].
  2249 ** A result table should be deallocated using [sqlite3_free_table()].
  2250 **
  2251 ** ^(As an example of the result table format, suppose a query result
  2252 ** is as follows:
  2253 **
  2254 ** <blockquote><pre>
  2255 **        Name        | Age
  2256 **        -----------------------
  2257 **        Alice       | 43
  2258 **        Bob         | 28
  2259 **        Cindy       | 21
  2260 ** </pre></blockquote>
  2261 **
  2262 ** There are two column (M==2) and three rows (N==3).  Thus the
  2263 ** result table has 8 entries.  Suppose the result table is stored
  2264 ** in an array names azResult.  Then azResult holds this content:
  2265 **
  2266 ** <blockquote><pre>
  2267 **        azResult&#91;0] = "Name";
  2268 **        azResult&#91;1] = "Age";
  2269 **        azResult&#91;2] = "Alice";
  2270 **        azResult&#91;3] = "43";
  2271 **        azResult&#91;4] = "Bob";
  2272 **        azResult&#91;5] = "28";
  2273 **        azResult&#91;6] = "Cindy";
  2274 **        azResult&#91;7] = "21";
  2275 ** </pre></blockquote>)^
  2276 **
  2277 ** ^The sqlite3_get_table() function evaluates one or more
  2278 ** semicolon-separated SQL statements in the zero-terminated UTF-8
  2279 ** string of its 2nd parameter and returns a result table to the
  2280 ** pointer given in its 3rd parameter.
  2281 **
  2282 ** After the application has finished with the result from sqlite3_get_table(),
  2283 ** it must pass the result table pointer to sqlite3_free_table() in order to
  2284 ** release the memory that was malloced.  Because of the way the
  2285 ** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
  2286 ** function must not try to call [sqlite3_free()] directly.  Only
  2287 ** [sqlite3_free_table()] is able to release the memory properly and safely.
  2288 **
  2289 ** The sqlite3_get_table() interface is implemented as a wrapper around
  2290 ** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
  2291 ** to any internal data structures of SQLite.  It uses only the public
  2292 ** interface defined here.  As a consequence, errors that occur in the
  2293 ** wrapper layer outside of the internal [sqlite3_exec()] call are not
  2294 ** reflected in subsequent calls to [sqlite3_errcode()] or
  2295 ** [sqlite3_errmsg()].
  2296 */
  2297 SQLITE_API int sqlite3_get_table(
  2298   sqlite3 *db,          /* An open database */
  2299   const char *zSql,     /* SQL to be evaluated */
  2300   char ***pazResult,    /* Results of the query */
  2301   int *pnRow,           /* Number of result rows written here */
  2302   int *pnColumn,        /* Number of result columns written here */
  2303   char **pzErrmsg       /* Error msg written here */
  2304 );
  2305 SQLITE_API void sqlite3_free_table(char **result);
  2306 
  2307 /*
  2308 ** CAPI3REF: Formatted String Printing Functions
  2309 **
  2310 ** These routines are work-alikes of the "printf()" family of functions
  2311 ** from the standard C library.
  2312 **
  2313 ** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
  2314 ** results into memory obtained from [sqlite3_malloc()].
  2315 ** The strings returned by these two routines should be
  2316 ** released by [sqlite3_free()].  ^Both routines return a
  2317 ** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
  2318 ** memory to hold the resulting string.
  2319 **
  2320 ** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
  2321 ** the standard C library.  The result is written into the
  2322 ** buffer supplied as the second parameter whose size is given by
  2323 ** the first parameter. Note that the order of the
  2324 ** first two parameters is reversed from snprintf().)^  This is an
  2325 ** historical accident that cannot be fixed without breaking
  2326 ** backwards compatibility.  ^(Note also that sqlite3_snprintf()
  2327 ** returns a pointer to its buffer instead of the number of
  2328 ** characters actually written into the buffer.)^  We admit that
  2329 ** the number of characters written would be a more useful return
  2330 ** value but we cannot change the implementation of sqlite3_snprintf()
  2331 ** now without breaking compatibility.
  2332 **
  2333 ** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
  2334 ** guarantees that the buffer is always zero-terminated.  ^The first
  2335 ** parameter "n" is the total size of the buffer, including space for
  2336 ** the zero terminator.  So the longest string that can be completely
  2337 ** written will be n-1 characters.
  2338 **
  2339 ** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
  2340 **
  2341 ** These routines all implement some additional formatting
  2342 ** options that are useful for constructing SQL statements.
  2343 ** All of the usual printf() formatting options apply.  In addition, there
  2344 ** is are "%q", "%Q", and "%z" options.
  2345 **
  2346 ** ^(The %q option works like %s in that it substitutes a nul-terminated
  2347 ** string from the argument list.  But %q also doubles every '\'' character.
  2348 ** %q is designed for use inside a string literal.)^  By doubling each '\''
  2349 ** character it escapes that character and allows it to be inserted into
  2350 ** the string.
  2351 **
  2352 ** For example, assume the string variable zText contains text as follows:
  2353 **
  2354 ** <blockquote><pre>
  2355 **  char *zText = "It's a happy day!";
  2356 ** </pre></blockquote>
  2357 **
  2358 ** One can use this text in an SQL statement as follows:
  2359 **
  2360 ** <blockquote><pre>
  2361 **  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
  2362 **  sqlite3_exec(db, zSQL, 0, 0, 0);
  2363 **  sqlite3_free(zSQL);
  2364 ** </pre></blockquote>
  2365 **
  2366 ** Because the %q format string is used, the '\'' character in zText
  2367 ** is escaped and the SQL generated is as follows:
  2368 **
  2369 ** <blockquote><pre>
  2370 **  INSERT INTO table1 VALUES('It''s a happy day!')
  2371 ** </pre></blockquote>
  2372 **
  2373 ** This is correct.  Had we used %s instead of %q, the generated SQL
  2374 ** would have looked like this:
  2375 **
  2376 ** <blockquote><pre>
  2377 **  INSERT INTO table1 VALUES('It's a happy day!');
  2378 ** </pre></blockquote>
  2379 **
  2380 ** This second example is an SQL syntax error.  As a general rule you should
  2381 ** always use %q instead of %s when inserting text into a string literal.
  2382 **
  2383 ** ^(The %Q option works like %q except it also adds single quotes around
  2384 ** the outside of the total string.  Additionally, if the parameter in the
  2385 ** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
  2386 ** single quotes).)^  So, for example, one could say:
  2387 **
  2388 ** <blockquote><pre>
  2389 **  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
  2390 **  sqlite3_exec(db, zSQL, 0, 0, 0);
  2391 **  sqlite3_free(zSQL);
  2392 ** </pre></blockquote>
  2393 **
  2394 ** The code above will render a correct SQL statement in the zSQL
  2395 ** variable even if the zText variable is a NULL pointer.
  2396 **
  2397 ** ^(The "%z" formatting option works like "%s" but with the
  2398 ** addition that after the string has been read and copied into
  2399 ** the result, [sqlite3_free()] is called on the input string.)^
  2400 */
  2401 SQLITE_API char *sqlite3_mprintf(const char*,...);
  2402 SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
  2403 SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
  2404 SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
  2405 
  2406 /*
  2407 ** CAPI3REF: Memory Allocation Subsystem
  2408 **
  2409 ** The SQLite core uses these three routines for all of its own
  2410 ** internal memory allocation needs. "Core" in the previous sentence
  2411 ** does not include operating-system specific VFS implementation.  The
  2412 ** Windows VFS uses native malloc() and free() for some operations.
  2413 **
  2414 ** ^The sqlite3_malloc() routine returns a pointer to a block
  2415 ** of memory at least N bytes in length, where N is the parameter.
  2416 ** ^If sqlite3_malloc() is unable to obtain sufficient free
  2417 ** memory, it returns a NULL pointer.  ^If the parameter N to
  2418 ** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
  2419 ** a NULL pointer.
  2420 **
  2421 ** ^Calling sqlite3_free() with a pointer previously returned
  2422 ** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
  2423 ** that it might be reused.  ^The sqlite3_free() routine is
  2424 ** a no-op if is called with a NULL pointer.  Passing a NULL pointer
  2425 ** to sqlite3_free() is harmless.  After being freed, memory
  2426 ** should neither be read nor written.  Even reading previously freed
  2427 ** memory might result in a segmentation fault or other severe error.
  2428 ** Memory corruption, a segmentation fault, or other severe error
  2429 ** might result if sqlite3_free() is called with a non-NULL pointer that
  2430 ** was not obtained from sqlite3_malloc() or sqlite3_realloc().
  2431 **
  2432 ** ^(The sqlite3_realloc() interface attempts to resize a
  2433 ** prior memory allocation to be at least N bytes, where N is the
  2434 ** second parameter.  The memory allocation to be resized is the first
  2435 ** parameter.)^ ^ If the first parameter to sqlite3_realloc()
  2436 ** is a NULL pointer then its behavior is identical to calling
  2437 ** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc().
  2438 ** ^If the second parameter to sqlite3_realloc() is zero or
  2439 ** negative then the behavior is exactly the same as calling
  2440 ** sqlite3_free(P) where P is the first parameter to sqlite3_realloc().
  2441 ** ^sqlite3_realloc() returns a pointer to a memory allocation
  2442 ** of at least N bytes in size or NULL if sufficient memory is unavailable.
  2443 ** ^If M is the size of the prior allocation, then min(N,M) bytes
  2444 ** of the prior allocation are copied into the beginning of buffer returned
  2445 ** by sqlite3_realloc() and the prior allocation is freed.
  2446 ** ^If sqlite3_realloc() returns NULL, then the prior allocation
  2447 ** is not freed.
  2448 **
  2449 ** ^The memory returned by sqlite3_malloc() and sqlite3_realloc()
  2450 ** is always aligned to at least an 8 byte boundary, or to a
  2451 ** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
  2452 ** option is used.
  2453 **
  2454 ** In SQLite version 3.5.0 and 3.5.1, it was possible to define
  2455 ** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
  2456 ** implementation of these routines to be omitted.  That capability
  2457 ** is no longer provided.  Only built-in memory allocators can be used.
  2458 **
  2459 ** Prior to SQLite version 3.7.10, the Windows OS interface layer called
  2460 ** the system malloc() and free() directly when converting
  2461 ** filenames between the UTF-8 encoding used by SQLite
  2462 ** and whatever filename encoding is used by the particular Windows
  2463 ** installation.  Memory allocation errors were detected, but
  2464 ** they were reported back as [SQLITE_CANTOPEN] or
  2465 ** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
  2466 **
  2467 ** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
  2468 ** must be either NULL or else pointers obtained from a prior
  2469 ** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
  2470 ** not yet been released.
  2471 **
  2472 ** The application must not read or write any part of
  2473 ** a block of memory after it has been released using
  2474 ** [sqlite3_free()] or [sqlite3_realloc()].
  2475 */
  2476 SQLITE_API void *sqlite3_malloc(int);
  2477 SQLITE_API void *sqlite3_realloc(void*, int);
  2478 SQLITE_API void sqlite3_free(void*);
  2479 
  2480 /*
  2481 ** CAPI3REF: Memory Allocator Statistics
  2482 **
  2483 ** SQLite provides these two interfaces for reporting on the status
  2484 ** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
  2485 ** routines, which form the built-in memory allocation subsystem.
  2486 **
  2487 ** ^The [sqlite3_memory_used()] routine returns the number of bytes
  2488 ** of memory currently outstanding (malloced but not freed).
  2489 ** ^The [sqlite3_memory_highwater()] routine returns the maximum
  2490 ** value of [sqlite3_memory_used()] since the high-water mark
  2491 ** was last reset.  ^The values returned by [sqlite3_memory_used()] and
  2492 ** [sqlite3_memory_highwater()] include any overhead
  2493 ** added by SQLite in its implementation of [sqlite3_malloc()],
  2494 ** but not overhead added by the any underlying system library
  2495 ** routines that [sqlite3_malloc()] may call.
  2496 **
  2497 ** ^The memory high-water mark is reset to the current value of
  2498 ** [sqlite3_memory_used()] if and only if the parameter to
  2499 ** [sqlite3_memory_highwater()] is true.  ^The value returned
  2500 ** by [sqlite3_memory_highwater(1)] is the high-water mark
  2501 ** prior to the reset.
  2502 */
  2503 SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
  2504 SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
  2505 
  2506 /*
  2507 ** CAPI3REF: Pseudo-Random Number Generator
  2508 **
  2509 ** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
  2510 ** select random [ROWID | ROWIDs] when inserting new records into a table that
  2511 ** already uses the largest possible [ROWID].  The PRNG is also used for
  2512 ** the build-in random() and randomblob() SQL functions.  This interface allows
  2513 ** applications to access the same PRNG for other purposes.
  2514 **
  2515 ** ^A call to this routine stores N bytes of randomness into buffer P.
  2516 ** ^If N is less than one, then P can be a NULL pointer.
  2517 **
  2518 ** ^If this routine has not been previously called or if the previous
  2519 ** call had N less than one, then the PRNG is seeded using randomness
  2520 ** obtained from the xRandomness method of the default [sqlite3_vfs] object.
  2521 ** ^If the previous call to this routine had an N of 1 or more then
  2522 ** the pseudo-randomness is generated
  2523 ** internally and without recourse to the [sqlite3_vfs] xRandomness
  2524 ** method.
  2525 */
  2526 SQLITE_API void sqlite3_randomness(int N, void *P);
  2527 
  2528 /*
  2529 ** CAPI3REF: Compile-Time Authorization Callbacks
  2530 **
  2531 ** ^This routine registers an authorizer callback with a particular
  2532 ** [database connection], supplied in the first argument.
  2533 ** ^The authorizer callback is invoked as SQL statements are being compiled
  2534 ** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
  2535 ** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
  2536 ** points during the compilation process, as logic is being created
  2537 ** to perform various actions, the authorizer callback is invoked to
  2538 ** see if those actions are allowed.  ^The authorizer callback should
  2539 ** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
  2540 ** specific action but allow the SQL statement to continue to be
  2541 ** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
  2542 ** rejected with an error.  ^If the authorizer callback returns
  2543 ** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
  2544 ** then the [sqlite3_prepare_v2()] or equivalent call that triggered
  2545 ** the authorizer will fail with an error message.
  2546 **
  2547 ** When the callback returns [SQLITE_OK], that means the operation
  2548 ** requested is ok.  ^When the callback returns [SQLITE_DENY], the
  2549 ** [sqlite3_prepare_v2()] or equivalent call that triggered the
  2550 ** authorizer will fail with an error message explaining that
  2551 ** access is denied. 
  2552 **
  2553 ** ^The first parameter to the authorizer callback is a copy of the third
  2554 ** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
  2555 ** to the callback is an integer [SQLITE_COPY | action code] that specifies
  2556 ** the particular action to be authorized. ^The third through sixth parameters
  2557 ** to the callback are zero-terminated strings that contain additional
  2558 ** details about the action to be authorized.
  2559 **
  2560 ** ^If the action code is [SQLITE_READ]
  2561 ** and the callback returns [SQLITE_IGNORE] then the
  2562 ** [prepared statement] statement is constructed to substitute
  2563 ** a NULL value in place of the table column that would have
  2564 ** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
  2565 ** return can be used to deny an untrusted user access to individual
  2566 ** columns of a table.
  2567 ** ^If the action code is [SQLITE_DELETE] and the callback returns
  2568 ** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
  2569 ** [truncate optimization] is disabled and all rows are deleted individually.
  2570 **
  2571 ** An authorizer is used when [sqlite3_prepare | preparing]
  2572 ** SQL statements from an untrusted source, to ensure that the SQL statements
  2573 ** do not try to access data they are not allowed to see, or that they do not
  2574 ** try to execute malicious statements that damage the database.  For
  2575 ** example, an application may allow a user to enter arbitrary
  2576 ** SQL queries for evaluation by a database.  But the application does
  2577 ** not want the user to be able to make arbitrary changes to the
  2578 ** database.  An authorizer could then be put in place while the
  2579 ** user-entered SQL is being [sqlite3_prepare | prepared] that
  2580 ** disallows everything except [SELECT] statements.
  2581 **
  2582 ** Applications that need to process SQL from untrusted sources
  2583 ** might also consider lowering resource limits using [sqlite3_limit()]
  2584 ** and limiting database size using the [max_page_count] [PRAGMA]
  2585 ** in addition to using an authorizer.
  2586 **
  2587 ** ^(Only a single authorizer can be in place on a database connection
  2588 ** at a time.  Each call to sqlite3_set_authorizer overrides the
  2589 ** previous call.)^  ^Disable the authorizer by installing a NULL callback.
  2590 ** The authorizer is disabled by default.
  2591 **
  2592 ** The authorizer callback must not do anything that will modify
  2593 ** the database connection that invoked the authorizer callback.
  2594 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2595 ** database connections for the meaning of "modify" in this paragraph.
  2596 **
  2597 ** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
  2598 ** statement might be re-prepared during [sqlite3_step()] due to a 
  2599 ** schema change.  Hence, the application should ensure that the
  2600 ** correct authorizer callback remains in place during the [sqlite3_step()].
  2601 **
  2602 ** ^Note that the authorizer callback is invoked only during
  2603 ** [sqlite3_prepare()] or its variants.  Authorization is not
  2604 ** performed during statement evaluation in [sqlite3_step()], unless
  2605 ** as stated in the previous paragraph, sqlite3_step() invokes
  2606 ** sqlite3_prepare_v2() to reprepare a statement after a schema change.
  2607 */
  2608 SQLITE_API int sqlite3_set_authorizer(
  2609   sqlite3*,
  2610   int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
  2611   void *pUserData
  2612 );
  2613 
  2614 /*
  2615 ** CAPI3REF: Authorizer Return Codes
  2616 **
  2617 ** The [sqlite3_set_authorizer | authorizer callback function] must
  2618 ** return either [SQLITE_OK] or one of these two constants in order
  2619 ** to signal SQLite whether or not the action is permitted.  See the
  2620 ** [sqlite3_set_authorizer | authorizer documentation] for additional
  2621 ** information.
  2622 **
  2623 ** Note that SQLITE_IGNORE is also used as a [conflict resolution mode]
  2624 ** returned from the [sqlite3_vtab_on_conflict()] interface.
  2625 */
  2626 #define SQLITE_DENY   1   /* Abort the SQL statement with an error */
  2627 #define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */
  2628 
  2629 /*
  2630 ** CAPI3REF: Authorizer Action Codes
  2631 **
  2632 ** The [sqlite3_set_authorizer()] interface registers a callback function
  2633 ** that is invoked to authorize certain SQL statement actions.  The
  2634 ** second parameter to the callback is an integer code that specifies
  2635 ** what action is being authorized.  These are the integer action codes that
  2636 ** the authorizer callback may be passed.
  2637 **
  2638 ** These action code values signify what kind of operation is to be
  2639 ** authorized.  The 3rd and 4th parameters to the authorization
  2640 ** callback function will be parameters or NULL depending on which of these
  2641 ** codes is used as the second parameter.  ^(The 5th parameter to the
  2642 ** authorizer callback is the name of the database ("main", "temp",
  2643 ** etc.) if applicable.)^  ^The 6th parameter to the authorizer callback
  2644 ** is the name of the inner-most trigger or view that is responsible for
  2645 ** the access attempt or NULL if this access attempt is directly from
  2646 ** top-level SQL code.
  2647 */
  2648 /******************************************* 3rd ************ 4th ***********/
  2649 #define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
  2650 #define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
  2651 #define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
  2652 #define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
  2653 #define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
  2654 #define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
  2655 #define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
  2656 #define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
  2657 #define SQLITE_DELETE                9   /* Table Name      NULL            */
  2658 #define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
  2659 #define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
  2660 #define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
  2661 #define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
  2662 #define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
  2663 #define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
  2664 #define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
  2665 #define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
  2666 #define SQLITE_INSERT               18   /* Table Name      NULL            */
  2667 #define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
  2668 #define SQLITE_READ                 20   /* Table Name      Column Name     */
  2669 #define SQLITE_SELECT               21   /* NULL            NULL            */
  2670 #define SQLITE_TRANSACTION          22   /* Operation       NULL            */
  2671 #define SQLITE_UPDATE               23   /* Table Name      Column Name     */
  2672 #define SQLITE_ATTACH               24   /* Filename        NULL            */
  2673 #define SQLITE_DETACH               25   /* Database Name   NULL            */
  2674 #define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
  2675 #define SQLITE_REINDEX              27   /* Index Name      NULL            */
  2676 #define SQLITE_ANALYZE              28   /* Table Name      NULL            */
  2677 #define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
  2678 #define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
  2679 #define SQLITE_FUNCTION             31   /* NULL            Function Name   */
  2680 #define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
  2681 #define SQLITE_COPY                  0   /* No longer used */
  2682 #define SQLITE_RECURSIVE            33   /* NULL            NULL            */
  2683 
  2684 /*
  2685 ** CAPI3REF: Tracing And Profiling Functions
  2686 **
  2687 ** These routines register callback functions that can be used for
  2688 ** tracing and profiling the execution of SQL statements.
  2689 **
  2690 ** ^The callback function registered by sqlite3_trace() is invoked at
  2691 ** various times when an SQL statement is being run by [sqlite3_step()].
  2692 ** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
  2693 ** SQL statement text as the statement first begins executing.
  2694 ** ^(Additional sqlite3_trace() callbacks might occur
  2695 ** as each triggered subprogram is entered.  The callbacks for triggers
  2696 ** contain a UTF-8 SQL comment that identifies the trigger.)^
  2697 **
  2698 ** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
  2699 ** the length of [bound parameter] expansion in the output of sqlite3_trace().
  2700 **
  2701 ** ^The callback function registered by sqlite3_profile() is invoked
  2702 ** as each SQL statement finishes.  ^The profile callback contains
  2703 ** the original statement text and an estimate of wall-clock time
  2704 ** of how long that statement took to run.  ^The profile callback
  2705 ** time is in units of nanoseconds, however the current implementation
  2706 ** is only capable of millisecond resolution so the six least significant
  2707 ** digits in the time are meaningless.  Future versions of SQLite
  2708 ** might provide greater resolution on the profiler callback.  The
  2709 ** sqlite3_profile() function is considered experimental and is
  2710 ** subject to change in future versions of SQLite.
  2711 */
  2712 SQLITE_API void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
  2713 SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
  2714    void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
  2715 
  2716 /*
  2717 ** CAPI3REF: Query Progress Callbacks
  2718 **
  2719 ** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
  2720 ** function X to be invoked periodically during long running calls to
  2721 ** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
  2722 ** database connection D.  An example use for this
  2723 ** interface is to keep a GUI updated during a large query.
  2724 **
  2725 ** ^The parameter P is passed through as the only parameter to the 
  2726 ** callback function X.  ^The parameter N is the approximate number of 
  2727 ** [virtual machine instructions] that are evaluated between successive
  2728 ** invocations of the callback X.  ^If N is less than one then the progress
  2729 ** handler is disabled.
  2730 **
  2731 ** ^Only a single progress handler may be defined at one time per
  2732 ** [database connection]; setting a new progress handler cancels the
  2733 ** old one.  ^Setting parameter X to NULL disables the progress handler.
  2734 ** ^The progress handler is also disabled by setting N to a value less
  2735 ** than 1.
  2736 **
  2737 ** ^If the progress callback returns non-zero, the operation is
  2738 ** interrupted.  This feature can be used to implement a
  2739 ** "Cancel" button on a GUI progress dialog box.
  2740 **
  2741 ** The progress handler callback must not do anything that will modify
  2742 ** the database connection that invoked the progress handler.
  2743 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2744 ** database connections for the meaning of "modify" in this paragraph.
  2745 **
  2746 */
  2747 SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
  2748 
  2749 /*
  2750 ** CAPI3REF: Opening A New Database Connection
  2751 **
  2752 ** ^These routines open an SQLite database file as specified by the 
  2753 ** filename argument. ^The filename argument is interpreted as UTF-8 for
  2754 ** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
  2755 ** order for sqlite3_open16(). ^(A [database connection] handle is usually
  2756 ** returned in *ppDb, even if an error occurs.  The only exception is that
  2757 ** if SQLite is unable to allocate memory to hold the [sqlite3] object,
  2758 ** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
  2759 ** object.)^ ^(If the database is opened (and/or created) successfully, then
  2760 ** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.)^ ^The
  2761 ** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
  2762 ** an English language description of the error following a failure of any
  2763 ** of the sqlite3_open() routines.
  2764 **
  2765 ** ^The default encoding for the database will be UTF-8 if
  2766 ** sqlite3_open() or sqlite3_open_v2() is called and
  2767 ** UTF-16 in the native byte order if sqlite3_open16() is used.
  2768 **
  2769 ** Whether or not an error occurs when it is opened, resources
  2770 ** associated with the [database connection] handle should be released by
  2771 ** passing it to [sqlite3_close()] when it is no longer required.
  2772 **
  2773 ** The sqlite3_open_v2() interface works like sqlite3_open()
  2774 ** except that it accepts two additional parameters for additional control
  2775 ** over the new database connection.  ^(The flags parameter to
  2776 ** sqlite3_open_v2() can take one of
  2777 ** the following three values, optionally combined with the 
  2778 ** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
  2779 ** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
  2780 **
  2781 ** <dl>
  2782 ** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
  2783 ** <dd>The database is opened in read-only mode.  If the database does not
  2784 ** already exist, an error is returned.</dd>)^
  2785 **
  2786 ** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
  2787 ** <dd>The database is opened for reading and writing if possible, or reading
  2788 ** only if the file is write protected by the operating system.  In either
  2789 ** case the database must already exist, otherwise an error is returned.</dd>)^
  2790 **
  2791 ** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
  2792 ** <dd>The database is opened for reading and writing, and is created if
  2793 ** it does not already exist. This is the behavior that is always used for
  2794 ** sqlite3_open() and sqlite3_open16().</dd>)^
  2795 ** </dl>
  2796 **
  2797 ** If the 3rd parameter to sqlite3_open_v2() is not one of the
  2798 ** combinations shown above optionally combined with other
  2799 ** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
  2800 ** then the behavior is undefined.
  2801 **
  2802 ** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
  2803 ** opens in the multi-thread [threading mode] as long as the single-thread
  2804 ** mode has not been set at compile-time or start-time.  ^If the
  2805 ** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
  2806 ** in the serialized [threading mode] unless single-thread was
  2807 ** previously selected at compile-time or start-time.
  2808 ** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
  2809 ** eligible to use [shared cache mode], regardless of whether or not shared
  2810 ** cache is enabled using [sqlite3_enable_shared_cache()].  ^The
  2811 ** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
  2812 ** participate in [shared cache mode] even if it is enabled.
  2813 **
  2814 ** ^The fourth parameter to sqlite3_open_v2() is the name of the
  2815 ** [sqlite3_vfs] object that defines the operating system interface that
  2816 ** the new database connection should use.  ^If the fourth parameter is
  2817 ** a NULL pointer then the default [sqlite3_vfs] object is used.
  2818 **
  2819 ** ^If the filename is ":memory:", then a private, temporary in-memory database
  2820 ** is created for the connection.  ^This in-memory database will vanish when
  2821 ** the database connection is closed.  Future versions of SQLite might
  2822 ** make use of additional special filenames that begin with the ":" character.
  2823 ** It is recommended that when a database filename actually does begin with
  2824 ** a ":" character you should prefix the filename with a pathname such as
  2825 ** "./" to avoid ambiguity.
  2826 **
  2827 ** ^If the filename is an empty string, then a private, temporary
  2828 ** on-disk database will be created.  ^This private database will be
  2829 ** automatically deleted as soon as the database connection is closed.
  2830 **
  2831 ** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
  2832 **
  2833 ** ^If [URI filename] interpretation is enabled, and the filename argument
  2834 ** begins with "file:", then the filename is interpreted as a URI. ^URI
  2835 ** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
  2836 ** set in the fourth argument to sqlite3_open_v2(), or if it has
  2837 ** been enabled globally using the [SQLITE_CONFIG_URI] option with the
  2838 ** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
  2839 ** As of SQLite version 3.7.7, URI filename interpretation is turned off
  2840 ** by default, but future releases of SQLite might enable URI filename
  2841 ** interpretation by default.  See "[URI filenames]" for additional
  2842 ** information.
  2843 **
  2844 ** URI filenames are parsed according to RFC 3986. ^If the URI contains an
  2845 ** authority, then it must be either an empty string or the string 
  2846 ** "localhost". ^If the authority is not an empty string or "localhost", an 
  2847 ** error is returned to the caller. ^The fragment component of a URI, if 
  2848 ** present, is ignored.
  2849 **
  2850 ** ^SQLite uses the path component of the URI as the name of the disk file
  2851 ** which contains the database. ^If the path begins with a '/' character, 
  2852 ** then it is interpreted as an absolute path. ^If the path does not begin 
  2853 ** with a '/' (meaning that the authority section is omitted from the URI)
  2854 ** then the path is interpreted as a relative path. 
  2855 ** ^On windows, the first component of an absolute path 
  2856 ** is a drive specification (e.g. "C:").
  2857 **
  2858 ** [[core URI query parameters]]
  2859 ** The query component of a URI may contain parameters that are interpreted
  2860 ** either by SQLite itself, or by a [VFS | custom VFS implementation].
  2861 ** SQLite interprets the following three query parameters:
  2862 **
  2863 ** <ul>
  2864 **   <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
  2865 **     a VFS object that provides the operating system interface that should
  2866 **     be used to access the database file on disk. ^If this option is set to
  2867 **     an empty string the default VFS object is used. ^Specifying an unknown
  2868 **     VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
  2869 **     present, then the VFS specified by the option takes precedence over
  2870 **     the value passed as the fourth parameter to sqlite3_open_v2().
  2871 **
  2872 **   <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
  2873 **     "rwc", or "memory". Attempting to set it to any other value is
  2874 **     an error)^. 
  2875 **     ^If "ro" is specified, then the database is opened for read-only 
  2876 **     access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the 
  2877 **     third argument to sqlite3_open_v2(). ^If the mode option is set to 
  2878 **     "rw", then the database is opened for read-write (but not create) 
  2879 **     access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had 
  2880 **     been set. ^Value "rwc" is equivalent to setting both 
  2881 **     SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE.  ^If the mode option is
  2882 **     set to "memory" then a pure [in-memory database] that never reads
  2883 **     or writes from disk is used. ^It is an error to specify a value for
  2884 **     the mode parameter that is less restrictive than that specified by
  2885 **     the flags passed in the third parameter to sqlite3_open_v2().
  2886 **
  2887 **   <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
  2888 **     "private". ^Setting it to "shared" is equivalent to setting the
  2889 **     SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
  2890 **     sqlite3_open_v2(). ^Setting the cache parameter to "private" is 
  2891 **     equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
  2892 **     ^If sqlite3_open_v2() is used and the "cache" parameter is present in
  2893 **     a URI filename, its value overrides any behavior requested by setting
  2894 **     SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
  2895 **
  2896 **  <li> <b>psow</b>: ^The psow parameter may be "true" (or "on" or "yes" or
  2897 **     "1") or "false" (or "off" or "no" or "0") to indicate that the
  2898 **     [powersafe overwrite] property does or does not apply to the
  2899 **     storage media on which the database file resides.  ^The psow query
  2900 **     parameter only works for the built-in unix and Windows VFSes.
  2901 **
  2902 **  <li> <b>nolock</b>: ^The nolock parameter is a boolean query parameter
  2903 **     which if set disables file locking in rollback journal modes.  This
  2904 **     is useful for accessing a database on a filesystem that does not
  2905 **     support locking.  Caution:  Database corruption might result if two
  2906 **     or more processes write to the same database and any one of those
  2907 **     processes uses nolock=1.
  2908 **
  2909 **  <li> <b>immutable</b>: ^The immutable parameter is a boolean query
  2910 **     parameter that indicates that the database file is stored on
  2911 **     read-only media.  ^When immutable is set, SQLite assumes that the
  2912 **     database file cannot be changed, even by a process with higher
  2913 **     privilege, and so the database is opened read-only and all locking
  2914 **     and change detection is disabled.  Caution: Setting the immutable
  2915 **     property on a database file that does in fact change can result
  2916 **     in incorrect query results and/or [SQLITE_CORRUPT] errors.
  2917 **     See also: [SQLITE_IOCAP_IMMUTABLE].
  2918 **       
  2919 ** </ul>
  2920 **
  2921 ** ^Specifying an unknown parameter in the query component of a URI is not an
  2922 ** error.  Future versions of SQLite might understand additional query
  2923 ** parameters.  See "[query parameters with special meaning to SQLite]" for
  2924 ** additional information.
  2925 **
  2926 ** [[URI filename examples]] <h3>URI filename examples</h3>
  2927 **
  2928 ** <table border="1" align=center cellpadding=5>
  2929 ** <tr><th> URI filenames <th> Results
  2930 ** <tr><td> file:data.db <td> 
  2931 **          Open the file "data.db" in the current directory.
  2932 ** <tr><td> file:/home/fred/data.db<br>
  2933 **          file:///home/fred/data.db <br> 
  2934 **          file://localhost/home/fred/data.db <br> <td> 
  2935 **          Open the database file "/home/fred/data.db".
  2936 ** <tr><td> file://darkstar/home/fred/data.db <td> 
  2937 **          An error. "darkstar" is not a recognized authority.
  2938 ** <tr><td style="white-space:nowrap"> 
  2939 **          file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
  2940 **     <td> Windows only: Open the file "data.db" on fred's desktop on drive
  2941 **          C:. Note that the %20 escaping in this example is not strictly 
  2942 **          necessary - space characters can be used literally
  2943 **          in URI filenames.
  2944 ** <tr><td> file:data.db?mode=ro&cache=private <td> 
  2945 **          Open file "data.db" in the current directory for read-only access.
  2946 **          Regardless of whether or not shared-cache mode is enabled by
  2947 **          default, use a private cache.
  2948 ** <tr><td> file:/home/fred/data.db?vfs=unix-dotfile <td>
  2949 **          Open file "/home/fred/data.db". Use the special VFS "unix-dotfile"
  2950 **          that uses dot-files in place of posix advisory locking.
  2951 ** <tr><td> file:data.db?mode=readonly <td> 
  2952 **          An error. "readonly" is not a valid option for the "mode" parameter.
  2953 ** </table>
  2954 **
  2955 ** ^URI hexadecimal escape sequences (%HH) are supported within the path and
  2956 ** query components of a URI. A hexadecimal escape sequence consists of a
  2957 ** percent sign - "%" - followed by exactly two hexadecimal digits 
  2958 ** specifying an octet value. ^Before the path or query components of a
  2959 ** URI filename are interpreted, they are encoded using UTF-8 and all 
  2960 ** hexadecimal escape sequences replaced by a single byte containing the
  2961 ** corresponding octet. If this process generates an invalid UTF-8 encoding,
  2962 ** the results are undefined.
  2963 **
  2964 ** <b>Note to Windows users:</b>  The encoding used for the filename argument
  2965 ** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
  2966 ** codepage is currently defined.  Filenames containing international
  2967 ** characters must be converted to UTF-8 prior to passing them into
  2968 ** sqlite3_open() or sqlite3_open_v2().
  2969 **
  2970 ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  2971 ** prior to calling sqlite3_open() or sqlite3_open_v2().  Otherwise, various
  2972 ** features that require the use of temporary files may fail.
  2973 **
  2974 ** See also: [sqlite3_temp_directory]
  2975 */
  2976 SQLITE_API int sqlite3_open(
  2977   const char *filename,   /* Database filename (UTF-8) */
  2978   sqlite3 **ppDb          /* OUT: SQLite db handle */
  2979 );
  2980 SQLITE_API int sqlite3_open16(
  2981   const void *filename,   /* Database filename (UTF-16) */
  2982   sqlite3 **ppDb          /* OUT: SQLite db handle */
  2983 );
  2984 SQLITE_API int sqlite3_open_v2(
  2985   const char *filename,   /* Database filename (UTF-8) */
  2986   sqlite3 **ppDb,         /* OUT: SQLite db handle */
  2987   int flags,              /* Flags */
  2988   const char *zVfs        /* Name of VFS module to use */
  2989 );
  2990 
  2991 /*
  2992 ** CAPI3REF: Obtain Values For URI Parameters
  2993 **
  2994 ** These are utility routines, useful to VFS implementations, that check
  2995 ** to see if a database file was a URI that contained a specific query 
  2996 ** parameter, and if so obtains the value of that query parameter.
  2997 **
  2998 ** If F is the database filename pointer passed into the xOpen() method of 
  2999 ** a VFS implementation when the flags parameter to xOpen() has one or 
  3000 ** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
  3001 ** P is the name of the query parameter, then
  3002 ** sqlite3_uri_parameter(F,P) returns the value of the P
  3003 ** parameter if it exists or a NULL pointer if P does not appear as a 
  3004 ** query parameter on F.  If P is a query parameter of F
  3005 ** has no explicit value, then sqlite3_uri_parameter(F,P) returns
  3006 ** a pointer to an empty string.
  3007 **
  3008 ** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
  3009 ** parameter and returns true (1) or false (0) according to the value
  3010 ** of P.  The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
  3011 ** value of query parameter P is one of "yes", "true", or "on" in any
  3012 ** case or if the value begins with a non-zero number.  The 
  3013 ** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
  3014 ** query parameter P is one of "no", "false", or "off" in any case or
  3015 ** if the value begins with a numeric zero.  If P is not a query
  3016 ** parameter on F or if the value of P is does not match any of the
  3017 ** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
  3018 **
  3019 ** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
  3020 ** 64-bit signed integer and returns that integer, or D if P does not
  3021 ** exist.  If the value of P is something other than an integer, then
  3022 ** zero is returned.
  3023 ** 
  3024 ** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
  3025 ** sqlite3_uri_boolean(F,P,B) returns B.  If F is not a NULL pointer and
  3026 ** is not a database file pathname pointer that SQLite passed into the xOpen
  3027 ** VFS method, then the behavior of this routine is undefined and probably
  3028 ** undesirable.
  3029 */
  3030 SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
  3031 SQLITE_API int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
  3032 SQLITE_API sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
  3033 
  3034 
  3035 /*
  3036 ** CAPI3REF: Error Codes And Messages
  3037 **
  3038 ** ^The sqlite3_errcode() interface returns the numeric [result code] or
  3039 ** [extended result code] for the most recent failed sqlite3_* API call
  3040 ** associated with a [database connection]. If a prior API call failed
  3041 ** but the most recent API call succeeded, the return value from
  3042 ** sqlite3_errcode() is undefined.  ^The sqlite3_extended_errcode()
  3043 ** interface is the same except that it always returns the 
  3044 ** [extended result code] even when extended result codes are
  3045 ** disabled.
  3046 **
  3047 ** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
  3048 ** text that describes the error, as either UTF-8 or UTF-16 respectively.
  3049 ** ^(Memory to hold the error message string is managed internally.
  3050 ** The application does not need to worry about freeing the result.
  3051 ** However, the error string might be overwritten or deallocated by
  3052 ** subsequent calls to other SQLite interface functions.)^
  3053 **
  3054 ** ^The sqlite3_errstr() interface returns the English-language text
  3055 ** that describes the [result code], as UTF-8.
  3056 ** ^(Memory to hold the error message string is managed internally
  3057 ** and must not be freed by the application)^.
  3058 **
  3059 ** When the serialized [threading mode] is in use, it might be the
  3060 ** case that a second error occurs on a separate thread in between
  3061 ** the time of the first error and the call to these interfaces.
  3062 ** When that happens, the second error will be reported since these
  3063 ** interfaces always report the most recent result.  To avoid
  3064 ** this, each thread can obtain exclusive use of the [database connection] D
  3065 ** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
  3066 ** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
  3067 ** all calls to the interfaces listed here are completed.
  3068 **
  3069 ** If an interface fails with SQLITE_MISUSE, that means the interface
  3070 ** was invoked incorrectly by the application.  In that case, the
  3071 ** error code and message may or may not be set.
  3072 */
  3073 SQLITE_API int sqlite3_errcode(sqlite3 *db);
  3074 SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
  3075 SQLITE_API const char *sqlite3_errmsg(sqlite3*);
  3076 SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
  3077 SQLITE_API const char *sqlite3_errstr(int);
  3078 
  3079 /*
  3080 ** CAPI3REF: SQL Statement Object
  3081 ** KEYWORDS: {prepared statement} {prepared statements}
  3082 **
  3083 ** An instance of this object represents a single SQL statement.
  3084 ** This object is variously known as a "prepared statement" or a
  3085 ** "compiled SQL statement" or simply as a "statement".
  3086 **
  3087 ** The life of a statement object goes something like this:
  3088 **
  3089 ** <ol>
  3090 ** <li> Create the object using [sqlite3_prepare_v2()] or a related
  3091 **      function.
  3092 ** <li> Bind values to [host parameters] using the sqlite3_bind_*()
  3093 **      interfaces.
  3094 ** <li> Run the SQL by calling [sqlite3_step()] one or more times.
  3095 ** <li> Reset the statement using [sqlite3_reset()] then go back
  3096 **      to step 2.  Do this zero or more times.
  3097 ** <li> Destroy the object using [sqlite3_finalize()].
  3098 ** </ol>
  3099 **
  3100 ** Refer to documentation on individual methods above for additional
  3101 ** information.
  3102 */
  3103 typedef struct sqlite3_stmt sqlite3_stmt;
  3104 
  3105 /*
  3106 ** CAPI3REF: Run-time Limits
  3107 **
  3108 ** ^(This interface allows the size of various constructs to be limited
  3109 ** on a connection by connection basis.  The first parameter is the
  3110 ** [database connection] whose limit is to be set or queried.  The
  3111 ** second parameter is one of the [limit categories] that define a
  3112 ** class of constructs to be size limited.  The third parameter is the
  3113 ** new limit for that construct.)^
  3114 **
  3115 ** ^If the new limit is a negative number, the limit is unchanged.
  3116 ** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a 
  3117 ** [limits | hard upper bound]
  3118 ** set at compile-time by a C preprocessor macro called
  3119 ** [limits | SQLITE_MAX_<i>NAME</i>].
  3120 ** (The "_LIMIT_" in the name is changed to "_MAX_".))^
  3121 ** ^Attempts to increase a limit above its hard upper bound are
  3122 ** silently truncated to the hard upper bound.
  3123 **
  3124 ** ^Regardless of whether or not the limit was changed, the 
  3125 ** [sqlite3_limit()] interface returns the prior value of the limit.
  3126 ** ^Hence, to find the current value of a limit without changing it,
  3127 ** simply invoke this interface with the third parameter set to -1.
  3128 **
  3129 ** Run-time limits are intended for use in applications that manage
  3130 ** both their own internal database and also databases that are controlled
  3131 ** by untrusted external sources.  An example application might be a
  3132 ** web browser that has its own databases for storing history and
  3133 ** separate databases controlled by JavaScript applications downloaded
  3134 ** off the Internet.  The internal databases can be given the
  3135 ** large, default limits.  Databases managed by external sources can
  3136 ** be given much smaller limits designed to prevent a denial of service
  3137 ** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
  3138 ** interface to further control untrusted SQL.  The size of the database
  3139 ** created by an untrusted script can be contained using the
  3140 ** [max_page_count] [PRAGMA].
  3141 **
  3142 ** New run-time limit categories may be added in future releases.
  3143 */
  3144 SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
  3145 
  3146 /*
  3147 ** CAPI3REF: Run-Time Limit Categories
  3148 ** KEYWORDS: {limit category} {*limit categories}
  3149 **
  3150 ** These constants define various performance limits
  3151 ** that can be lowered at run-time using [sqlite3_limit()].
  3152 ** The synopsis of the meanings of the various limits is shown below.
  3153 ** Additional information is available at [limits | Limits in SQLite].
  3154 **
  3155 ** <dl>
  3156 ** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>
  3157 ** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
  3158 **
  3159 ** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
  3160 ** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
  3161 **
  3162 ** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>
  3163 ** <dd>The maximum number of columns in a table definition or in the
  3164 ** result set of a [SELECT] or the maximum number of columns in an index
  3165 ** or in an ORDER BY or GROUP BY clause.</dd>)^
  3166 **
  3167 ** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
  3168 ** <dd>The maximum depth of the parse tree on any expression.</dd>)^
  3169 **
  3170 ** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
  3171 ** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
  3172 **
  3173 ** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
  3174 ** <dd>The maximum number of instructions in a virtual machine program
  3175 ** used to implement an SQL statement.  This limit is not currently
  3176 ** enforced, though that might be added in some future release of
  3177 ** SQLite.</dd>)^
  3178 **
  3179 ** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
  3180 ** <dd>The maximum number of arguments on a function.</dd>)^
  3181 **
  3182 ** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
  3183 ** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
  3184 **
  3185 ** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]
  3186 ** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
  3187 ** <dd>The maximum length of the pattern argument to the [LIKE] or
  3188 ** [GLOB] operators.</dd>)^
  3189 **
  3190 ** [[SQLITE_LIMIT_VARIABLE_NUMBER]]
  3191 ** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
  3192 ** <dd>The maximum index number of any [parameter] in an SQL statement.)^
  3193 **
  3194 ** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
  3195 ** <dd>The maximum depth of recursion for triggers.</dd>)^
  3196 ** </dl>
  3197 */
  3198 #define SQLITE_LIMIT_LENGTH                    0
  3199 #define SQLITE_LIMIT_SQL_LENGTH                1
  3200 #define SQLITE_LIMIT_COLUMN                    2
  3201 #define SQLITE_LIMIT_EXPR_DEPTH                3
  3202 #define SQLITE_LIMIT_COMPOUND_SELECT           4
  3203 #define SQLITE_LIMIT_VDBE_OP                   5
  3204 #define SQLITE_LIMIT_FUNCTION_ARG              6
  3205 #define SQLITE_LIMIT_ATTACHED                  7
  3206 #define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
  3207 #define SQLITE_LIMIT_VARIABLE_NUMBER           9
  3208 #define SQLITE_LIMIT_TRIGGER_DEPTH            10
  3209 
  3210 /*
  3211 ** CAPI3REF: Compiling An SQL Statement
  3212 ** KEYWORDS: {SQL statement compiler}
  3213 **
  3214 ** To execute an SQL query, it must first be compiled into a byte-code
  3215 ** program using one of these routines.
  3216 **
  3217 ** The first argument, "db", is a [database connection] obtained from a
  3218 ** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
  3219 ** [sqlite3_open16()].  The database connection must not have been closed.
  3220 **
  3221 ** The second argument, "zSql", is the statement to be compiled, encoded
  3222 ** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
  3223 ** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
  3224 ** use UTF-16.
  3225 **
  3226 ** ^If the nByte argument is less than zero, then zSql is read up to the
  3227 ** first zero terminator. ^If nByte is non-negative, then it is the maximum
  3228 ** number of  bytes read from zSql.  ^When nByte is non-negative, the
  3229 ** zSql string ends at either the first '\000' or '\u0000' character or
  3230 ** the nByte-th byte, whichever comes first. If the caller knows
  3231 ** that the supplied string is nul-terminated, then there is a small
  3232 ** performance advantage to be gained by passing an nByte parameter that
  3233 ** is equal to the number of bytes in the input string <i>including</i>
  3234 ** the nul-terminator bytes as this saves SQLite from having to
  3235 ** make a copy of the input string.
  3236 **
  3237 ** ^If pzTail is not NULL then *pzTail is made to point to the first byte
  3238 ** past the end of the first SQL statement in zSql.  These routines only
  3239 ** compile the first statement in zSql, so *pzTail is left pointing to
  3240 ** what remains uncompiled.
  3241 **
  3242 ** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
  3243 ** executed using [sqlite3_step()].  ^If there is an error, *ppStmt is set
  3244 ** to NULL.  ^If the input text contains no SQL (if the input is an empty
  3245 ** string or a comment) then *ppStmt is set to NULL.
  3246 ** The calling procedure is responsible for deleting the compiled
  3247 ** SQL statement using [sqlite3_finalize()] after it has finished with it.
  3248 ** ppStmt may not be NULL.
  3249 **
  3250 ** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
  3251 ** otherwise an [error code] is returned.
  3252 **
  3253 ** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
  3254 ** recommended for all new programs. The two older interfaces are retained
  3255 ** for backwards compatibility, but their use is discouraged.
  3256 ** ^In the "v2" interfaces, the prepared statement
  3257 ** that is returned (the [sqlite3_stmt] object) contains a copy of the
  3258 ** original SQL text. This causes the [sqlite3_step()] interface to
  3259 ** behave differently in three ways:
  3260 **
  3261 ** <ol>
  3262 ** <li>
  3263 ** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
  3264 ** always used to do, [sqlite3_step()] will automatically recompile the SQL
  3265 ** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
  3266 ** retries will occur before sqlite3_step() gives up and returns an error.
  3267 ** </li>
  3268 **
  3269 ** <li>
  3270 ** ^When an error occurs, [sqlite3_step()] will return one of the detailed
  3271 ** [error codes] or [extended error codes].  ^The legacy behavior was that
  3272 ** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
  3273 ** and the application would have to make a second call to [sqlite3_reset()]
  3274 ** in order to find the underlying cause of the problem. With the "v2" prepare
  3275 ** interfaces, the underlying reason for the error is returned immediately.
  3276 ** </li>
  3277 **
  3278 ** <li>
  3279 ** ^If the specific value bound to [parameter | host parameter] in the 
  3280 ** WHERE clause might influence the choice of query plan for a statement,
  3281 ** then the statement will be automatically recompiled, as if there had been 
  3282 ** a schema change, on the first  [sqlite3_step()] call following any change
  3283 ** to the [sqlite3_bind_text | bindings] of that [parameter]. 
  3284 ** ^The specific value of WHERE-clause [parameter] might influence the 
  3285 ** choice of query plan if the parameter is the left-hand side of a [LIKE]
  3286 ** or [GLOB] operator or if the parameter is compared to an indexed column
  3287 ** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
  3288 ** </li>
  3289 ** </ol>
  3290 */
  3291 SQLITE_API int sqlite3_prepare(
  3292   sqlite3 *db,            /* Database handle */
  3293   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3294   int nByte,              /* Maximum length of zSql in bytes. */
  3295   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3296   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3297 );
  3298 SQLITE_API int sqlite3_prepare_v2(
  3299   sqlite3 *db,            /* Database handle */
  3300   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3301   int nByte,              /* Maximum length of zSql in bytes. */
  3302   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3303   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3304 );
  3305 SQLITE_API int sqlite3_prepare16(
  3306   sqlite3 *db,            /* Database handle */
  3307   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3308   int nByte,              /* Maximum length of zSql in bytes. */
  3309   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3310   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3311 );
  3312 SQLITE_API int sqlite3_prepare16_v2(
  3313   sqlite3 *db,            /* Database handle */
  3314   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3315   int nByte,              /* Maximum length of zSql in bytes. */
  3316   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3317   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3318 );
  3319 
  3320 /*
  3321 ** CAPI3REF: Retrieving Statement SQL
  3322 **
  3323 ** ^This interface can be used to retrieve a saved copy of the original
  3324 ** SQL text used to create a [prepared statement] if that statement was
  3325 ** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
  3326 */
  3327 SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);
  3328 
  3329 /*
  3330 ** CAPI3REF: Determine If An SQL Statement Writes The Database
  3331 **
  3332 ** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
  3333 ** and only if the [prepared statement] X makes no direct changes to
  3334 ** the content of the database file.
  3335 **
  3336 ** Note that [application-defined SQL functions] or
  3337 ** [virtual tables] might change the database indirectly as a side effect.  
  3338 ** ^(For example, if an application defines a function "eval()" that 
  3339 ** calls [sqlite3_exec()], then the following SQL statement would
  3340 ** change the database file through side-effects:
  3341 **
  3342 ** <blockquote><pre>
  3343 **    SELECT eval('DELETE FROM t1') FROM t2;
  3344 ** </pre></blockquote>
  3345 **
  3346 ** But because the [SELECT] statement does not change the database file
  3347 ** directly, sqlite3_stmt_readonly() would still return true.)^
  3348 **
  3349 ** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
  3350 ** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
  3351 ** since the statements themselves do not actually modify the database but
  3352 ** rather they control the timing of when other statements modify the 
  3353 ** database.  ^The [ATTACH] and [DETACH] statements also cause
  3354 ** sqlite3_stmt_readonly() to return true since, while those statements
  3355 ** change the configuration of a database connection, they do not make 
  3356 ** changes to the content of the database files on disk.
  3357 */
  3358 SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
  3359 
  3360 /*
  3361 ** CAPI3REF: Determine If A Prepared Statement Has Been Reset
  3362 **
  3363 ** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
  3364 ** [prepared statement] S has been stepped at least once using 
  3365 ** [sqlite3_step(S)] but has not run to completion and/or has not 
  3366 ** been reset using [sqlite3_reset(S)].  ^The sqlite3_stmt_busy(S)
  3367 ** interface returns false if S is a NULL pointer.  If S is not a 
  3368 ** NULL pointer and is not a pointer to a valid [prepared statement]
  3369 ** object, then the behavior is undefined and probably undesirable.
  3370 **
  3371 ** This interface can be used in combination [sqlite3_next_stmt()]
  3372 ** to locate all prepared statements associated with a database 
  3373 ** connection that are in need of being reset.  This can be used,
  3374 ** for example, in diagnostic routines to search for prepared 
  3375 ** statements that are holding a transaction open.
  3376 */
  3377 SQLITE_API int sqlite3_stmt_busy(sqlite3_stmt*);
  3378 
  3379 /*
  3380 ** CAPI3REF: Dynamically Typed Value Object
  3381 ** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
  3382 **
  3383 ** SQLite uses the sqlite3_value object to represent all values
  3384 ** that can be stored in a database table. SQLite uses dynamic typing
  3385 ** for the values it stores.  ^Values stored in sqlite3_value objects
  3386 ** can be integers, floating point values, strings, BLOBs, or NULL.
  3387 **
  3388 ** An sqlite3_value object may be either "protected" or "unprotected".
  3389 ** Some interfaces require a protected sqlite3_value.  Other interfaces
  3390 ** will accept either a protected or an unprotected sqlite3_value.
  3391 ** Every interface that accepts sqlite3_value arguments specifies
  3392 ** whether or not it requires a protected sqlite3_value.
  3393 **
  3394 ** The terms "protected" and "unprotected" refer to whether or not
  3395 ** a mutex is held.  An internal mutex is held for a protected
  3396 ** sqlite3_value object but no mutex is held for an unprotected
  3397 ** sqlite3_value object.  If SQLite is compiled to be single-threaded
  3398 ** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
  3399 ** or if SQLite is run in one of reduced mutex modes 
  3400 ** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
  3401 ** then there is no distinction between protected and unprotected
  3402 ** sqlite3_value objects and they can be used interchangeably.  However,
  3403 ** for maximum code portability it is recommended that applications
  3404 ** still make the distinction between protected and unprotected
  3405 ** sqlite3_value objects even when not strictly required.
  3406 **
  3407 ** ^The sqlite3_value objects that are passed as parameters into the
  3408 ** implementation of [application-defined SQL functions] are protected.
  3409 ** ^The sqlite3_value object returned by
  3410 ** [sqlite3_column_value()] is unprotected.
  3411 ** Unprotected sqlite3_value objects may only be used with
  3412 ** [sqlite3_result_value()] and [sqlite3_bind_value()].
  3413 ** The [sqlite3_value_blob | sqlite3_value_type()] family of
  3414 ** interfaces require protected sqlite3_value objects.
  3415 */
  3416 typedef struct Mem sqlite3_value;
  3417 
  3418 /*
  3419 ** CAPI3REF: SQL Function Context Object
  3420 **
  3421 ** The context in which an SQL function executes is stored in an
  3422 ** sqlite3_context object.  ^A pointer to an sqlite3_context object
  3423 ** is always first parameter to [application-defined SQL functions].
  3424 ** The application-defined SQL function implementation will pass this
  3425 ** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
  3426 ** [sqlite3_aggregate_context()], [sqlite3_user_data()],
  3427 ** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
  3428 ** and/or [sqlite3_set_auxdata()].
  3429 */
  3430 typedef struct sqlite3_context sqlite3_context;
  3431 
  3432 /*
  3433 ** CAPI3REF: Binding Values To Prepared Statements
  3434 ** KEYWORDS: {host parameter} {host parameters} {host parameter name}
  3435 ** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
  3436 **
  3437 ** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
  3438 ** literals may be replaced by a [parameter] that matches one of following
  3439 ** templates:
  3440 **
  3441 ** <ul>
  3442 ** <li>  ?
  3443 ** <li>  ?NNN
  3444 ** <li>  :VVV
  3445 ** <li>  @VVV
  3446 ** <li>  $VVV
  3447 ** </ul>
  3448 **
  3449 ** In the templates above, NNN represents an integer literal,
  3450 ** and VVV represents an alphanumeric identifier.)^  ^The values of these
  3451 ** parameters (also called "host parameter names" or "SQL parameters")
  3452 ** can be set using the sqlite3_bind_*() routines defined here.
  3453 **
  3454 ** ^The first argument to the sqlite3_bind_*() routines is always
  3455 ** a pointer to the [sqlite3_stmt] object returned from
  3456 ** [sqlite3_prepare_v2()] or its variants.
  3457 **
  3458 ** ^The second argument is the index of the SQL parameter to be set.
  3459 ** ^The leftmost SQL parameter has an index of 1.  ^When the same named
  3460 ** SQL parameter is used more than once, second and subsequent
  3461 ** occurrences have the same index as the first occurrence.
  3462 ** ^The index for named parameters can be looked up using the
  3463 ** [sqlite3_bind_parameter_index()] API if desired.  ^The index
  3464 ** for "?NNN" parameters is the value of NNN.
  3465 ** ^The NNN value must be between 1 and the [sqlite3_limit()]
  3466 ** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
  3467 **
  3468 ** ^The third argument is the value to bind to the parameter.
  3469 ** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3470 ** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
  3471 ** is ignored and the end result is the same as sqlite3_bind_null().
  3472 **
  3473 ** ^(In those routines that have a fourth argument, its value is the
  3474 ** number of bytes in the parameter.  To be clear: the value is the
  3475 ** number of <u>bytes</u> in the value, not the number of characters.)^
  3476 ** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3477 ** is negative, then the length of the string is
  3478 ** the number of bytes up to the first zero terminator.
  3479 ** If the fourth parameter to sqlite3_bind_blob() is negative, then
  3480 ** the behavior is undefined.
  3481 ** If a non-negative fourth parameter is provided to sqlite3_bind_text()
  3482 ** or sqlite3_bind_text16() then that parameter must be the byte offset
  3483 ** where the NUL terminator would occur assuming the string were NUL
  3484 ** terminated.  If any NUL characters occur at byte offsets less than 
  3485 ** the value of the fourth parameter then the resulting string value will
  3486 ** contain embedded NULs.  The result of expressions involving strings
  3487 ** with embedded NULs is undefined.
  3488 **
  3489 ** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
  3490 ** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
  3491 ** string after SQLite has finished with it.  ^The destructor is called
  3492 ** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
  3493 ** sqlite3_bind_text(), or sqlite3_bind_text16() fails.  
  3494 ** ^If the fifth argument is
  3495 ** the special value [SQLITE_STATIC], then SQLite assumes that the
  3496 ** information is in static, unmanaged space and does not need to be freed.
  3497 ** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
  3498 ** SQLite makes its own private copy of the data immediately, before
  3499 ** the sqlite3_bind_*() routine returns.
  3500 **
  3501 ** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
  3502 ** is filled with zeroes.  ^A zeroblob uses a fixed amount of memory
  3503 ** (just an integer to hold its size) while it is being processed.
  3504 ** Zeroblobs are intended to serve as placeholders for BLOBs whose
  3505 ** content is later written using
  3506 ** [sqlite3_blob_open | incremental BLOB I/O] routines.
  3507 ** ^A negative value for the zeroblob results in a zero-length BLOB.
  3508 **
  3509 ** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
  3510 ** for the [prepared statement] or with a prepared statement for which
  3511 ** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
  3512 ** then the call will return [SQLITE_MISUSE].  If any sqlite3_bind_()
  3513 ** routine is passed a [prepared statement] that has been finalized, the
  3514 ** result is undefined and probably harmful.
  3515 **
  3516 ** ^Bindings are not cleared by the [sqlite3_reset()] routine.
  3517 ** ^Unbound parameters are interpreted as NULL.
  3518 **
  3519 ** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
  3520 ** [error code] if anything goes wrong.
  3521 ** ^[SQLITE_RANGE] is returned if the parameter
  3522 ** index is out of range.  ^[SQLITE_NOMEM] is returned if malloc() fails.
  3523 **
  3524 ** See also: [sqlite3_bind_parameter_count()],
  3525 ** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
  3526 */
  3527 SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
  3528 SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
  3529 SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
  3530 SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
  3531 SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int);
  3532 SQLITE_API int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*));
  3533 SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
  3534 SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
  3535 SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
  3536 
  3537 /*
  3538 ** CAPI3REF: Number Of SQL Parameters
  3539 **
  3540 ** ^This routine can be used to find the number of [SQL parameters]
  3541 ** in a [prepared statement].  SQL parameters are tokens of the
  3542 ** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
  3543 ** placeholders for values that are [sqlite3_bind_blob | bound]
  3544 ** to the parameters at a later time.
  3545 **
  3546 ** ^(This routine actually returns the index of the largest (rightmost)
  3547 ** parameter. For all forms except ?NNN, this will correspond to the
  3548 ** number of unique parameters.  If parameters of the ?NNN form are used,
  3549 ** there may be gaps in the list.)^
  3550 **
  3551 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3552 ** [sqlite3_bind_parameter_name()], and
  3553 ** [sqlite3_bind_parameter_index()].
  3554 */
  3555 SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*);
  3556 
  3557 /*
  3558 ** CAPI3REF: Name Of A Host Parameter
  3559 **
  3560 ** ^The sqlite3_bind_parameter_name(P,N) interface returns
  3561 ** the name of the N-th [SQL parameter] in the [prepared statement] P.
  3562 ** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
  3563 ** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
  3564 ** respectively.
  3565 ** In other words, the initial ":" or "$" or "@" or "?"
  3566 ** is included as part of the name.)^
  3567 ** ^Parameters of the form "?" without a following integer have no name
  3568 ** and are referred to as "nameless" or "anonymous parameters".
  3569 **
  3570 ** ^The first host parameter has an index of 1, not 0.
  3571 **
  3572 ** ^If the value N is out of range or if the N-th parameter is
  3573 ** nameless, then NULL is returned.  ^The returned string is
  3574 ** always in UTF-8 encoding even if the named parameter was
  3575 ** originally specified as UTF-16 in [sqlite3_prepare16()] or
  3576 ** [sqlite3_prepare16_v2()].
  3577 **
  3578 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3579 ** [sqlite3_bind_parameter_count()], and
  3580 ** [sqlite3_bind_parameter_index()].
  3581 */
  3582 SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);
  3583 
  3584 /*
  3585 ** CAPI3REF: Index Of A Parameter With A Given Name
  3586 **
  3587 ** ^Return the index of an SQL parameter given its name.  ^The
  3588 ** index value returned is suitable for use as the second
  3589 ** parameter to [sqlite3_bind_blob|sqlite3_bind()].  ^A zero
  3590 ** is returned if no matching parameter is found.  ^The parameter
  3591 ** name must be given in UTF-8 even if the original statement
  3592 ** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
  3593 **
  3594 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3595 ** [sqlite3_bind_parameter_count()], and
  3596 ** [sqlite3_bind_parameter_index()].
  3597 */
  3598 SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
  3599 
  3600 /*
  3601 ** CAPI3REF: Reset All Bindings On A Prepared Statement
  3602 **
  3603 ** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
  3604 ** the [sqlite3_bind_blob | bindings] on a [prepared statement].
  3605 ** ^Use this routine to reset all host parameters to NULL.
  3606 */
  3607 SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*);
  3608 
  3609 /*
  3610 ** CAPI3REF: Number Of Columns In A Result Set
  3611 **
  3612 ** ^Return the number of columns in the result set returned by the
  3613 ** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
  3614 ** statement that does not return data (for example an [UPDATE]).
  3615 **
  3616 ** See also: [sqlite3_data_count()]
  3617 */
  3618 SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt);
  3619 
  3620 /*
  3621 ** CAPI3REF: Column Names In A Result Set
  3622 **
  3623 ** ^These routines return the name assigned to a particular column
  3624 ** in the result set of a [SELECT] statement.  ^The sqlite3_column_name()
  3625 ** interface returns a pointer to a zero-terminated UTF-8 string
  3626 ** and sqlite3_column_name16() returns a pointer to a zero-terminated
  3627 ** UTF-16 string.  ^The first parameter is the [prepared statement]
  3628 ** that implements the [SELECT] statement. ^The second parameter is the
  3629 ** column number.  ^The leftmost column is number 0.
  3630 **
  3631 ** ^The returned string pointer is valid until either the [prepared statement]
  3632 ** is destroyed by [sqlite3_finalize()] or until the statement is automatically
  3633 ** reprepared by the first call to [sqlite3_step()] for a particular run
  3634 ** or until the next call to
  3635 ** sqlite3_column_name() or sqlite3_column_name16() on the same column.
  3636 **
  3637 ** ^If sqlite3_malloc() fails during the processing of either routine
  3638 ** (for example during a conversion from UTF-8 to UTF-16) then a
  3639 ** NULL pointer is returned.
  3640 **
  3641 ** ^The name of a result column is the value of the "AS" clause for
  3642 ** that column, if there is an AS clause.  If there is no AS clause
  3643 ** then the name of the column is unspecified and may change from
  3644 ** one release of SQLite to the next.
  3645 */
  3646 SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
  3647 SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);
  3648 
  3649 /*
  3650 ** CAPI3REF: Source Of Data In A Query Result
  3651 **
  3652 ** ^These routines provide a means to determine the database, table, and
  3653 ** table column that is the origin of a particular result column in
  3654 ** [SELECT] statement.
  3655 ** ^The name of the database or table or column can be returned as
  3656 ** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
  3657 ** the database name, the _table_ routines return the table name, and
  3658 ** the origin_ routines return the column name.
  3659 ** ^The returned string is valid until the [prepared statement] is destroyed
  3660 ** using [sqlite3_finalize()] or until the statement is automatically
  3661 ** reprepared by the first call to [sqlite3_step()] for a particular run
  3662 ** or until the same information is requested
  3663 ** again in a different encoding.
  3664 **
  3665 ** ^The names returned are the original un-aliased names of the
  3666 ** database, table, and column.
  3667 **
  3668 ** ^The first argument to these interfaces is a [prepared statement].
  3669 ** ^These functions return information about the Nth result column returned by
  3670 ** the statement, where N is the second function argument.
  3671 ** ^The left-most column is column 0 for these routines.
  3672 **
  3673 ** ^If the Nth column returned by the statement is an expression or
  3674 ** subquery and is not a column value, then all of these functions return
  3675 ** NULL.  ^These routine might also return NULL if a memory allocation error
  3676 ** occurs.  ^Otherwise, they return the name of the attached database, table,
  3677 ** or column that query result column was extracted from.
  3678 **
  3679 ** ^As with all other SQLite APIs, those whose names end with "16" return
  3680 ** UTF-16 encoded strings and the other functions return UTF-8.
  3681 **
  3682 ** ^These APIs are only available if the library was compiled with the
  3683 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
  3684 **
  3685 ** If two or more threads call one or more of these routines against the same
  3686 ** prepared statement and column at the same time then the results are
  3687 ** undefined.
  3688 **
  3689 ** If two or more threads call one or more
  3690 ** [sqlite3_column_database_name | column metadata interfaces]
  3691 ** for the same [prepared statement] and result column
  3692 ** at the same time then the results are undefined.
  3693 */
  3694 SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int);
  3695 SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
  3696 SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int);
  3697 SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
  3698 SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
  3699 SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);
  3700 
  3701 /*
  3702 ** CAPI3REF: Declared Datatype Of A Query Result
  3703 **
  3704 ** ^(The first parameter is a [prepared statement].
  3705 ** If this statement is a [SELECT] statement and the Nth column of the
  3706 ** returned result set of that [SELECT] is a table column (not an
  3707 ** expression or subquery) then the declared type of the table
  3708 ** column is returned.)^  ^If the Nth column of the result set is an
  3709 ** expression or subquery, then a NULL pointer is returned.
  3710 ** ^The returned string is always UTF-8 encoded.
  3711 **
  3712 ** ^(For example, given the database schema:
  3713 **
  3714 ** CREATE TABLE t1(c1 VARIANT);
  3715 **
  3716 ** and the following statement to be compiled:
  3717 **
  3718 ** SELECT c1 + 1, c1 FROM t1;
  3719 **
  3720 ** this routine would return the string "VARIANT" for the second result
  3721 ** column (i==1), and a NULL pointer for the first result column (i==0).)^
  3722 **
  3723 ** ^SQLite uses dynamic run-time typing.  ^So just because a column
  3724 ** is declared to contain a particular type does not mean that the
  3725 ** data stored in that column is of the declared type.  SQLite is
  3726 ** strongly typed, but the typing is dynamic not static.  ^Type
  3727 ** is associated with individual values, not with the containers
  3728 ** used to hold those values.
  3729 */
  3730 SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int);
  3731 SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
  3732 
  3733 /*
  3734 ** CAPI3REF: Evaluate An SQL Statement
  3735 **
  3736 ** After a [prepared statement] has been prepared using either
  3737 ** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
  3738 ** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
  3739 ** must be called one or more times to evaluate the statement.
  3740 **
  3741 ** The details of the behavior of the sqlite3_step() interface depend
  3742 ** on whether the statement was prepared using the newer "v2" interface
  3743 ** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
  3744 ** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
  3745 ** new "v2" interface is recommended for new applications but the legacy
  3746 ** interface will continue to be supported.
  3747 **
  3748 ** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
  3749 ** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
  3750 ** ^With the "v2" interface, any of the other [result codes] or
  3751 ** [extended result codes] might be returned as well.
  3752 **
  3753 ** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
  3754 ** database locks it needs to do its job.  ^If the statement is a [COMMIT]
  3755 ** or occurs outside of an explicit transaction, then you can retry the
  3756 ** statement.  If the statement is not a [COMMIT] and occurs within an
  3757 ** explicit transaction then you should rollback the transaction before
  3758 ** continuing.
  3759 **
  3760 ** ^[SQLITE_DONE] means that the statement has finished executing
  3761 ** successfully.  sqlite3_step() should not be called again on this virtual
  3762 ** machine without first calling [sqlite3_reset()] to reset the virtual
  3763 ** machine back to its initial state.
  3764 **
  3765 ** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
  3766 ** is returned each time a new row of data is ready for processing by the
  3767 ** caller. The values may be accessed using the [column access functions].
  3768 ** sqlite3_step() is called again to retrieve the next row of data.
  3769 **
  3770 ** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
  3771 ** violation) has occurred.  sqlite3_step() should not be called again on
  3772 ** the VM. More information may be found by calling [sqlite3_errmsg()].
  3773 ** ^With the legacy interface, a more specific error code (for example,
  3774 ** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
  3775 ** can be obtained by calling [sqlite3_reset()] on the
  3776 ** [prepared statement].  ^In the "v2" interface,
  3777 ** the more specific error code is returned directly by sqlite3_step().
  3778 **
  3779 ** [SQLITE_MISUSE] means that the this routine was called inappropriately.
  3780 ** Perhaps it was called on a [prepared statement] that has
  3781 ** already been [sqlite3_finalize | finalized] or on one that had
  3782 ** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
  3783 ** be the case that the same database connection is being used by two or
  3784 ** more threads at the same moment in time.
  3785 **
  3786 ** For all versions of SQLite up to and including 3.6.23.1, a call to
  3787 ** [sqlite3_reset()] was required after sqlite3_step() returned anything
  3788 ** other than [SQLITE_ROW] before any subsequent invocation of
  3789 ** sqlite3_step().  Failure to reset the prepared statement using 
  3790 ** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
  3791 ** sqlite3_step().  But after version 3.6.23.1, sqlite3_step() began
  3792 ** calling [sqlite3_reset()] automatically in this circumstance rather
  3793 ** than returning [SQLITE_MISUSE].  This is not considered a compatibility
  3794 ** break because any application that ever receives an SQLITE_MISUSE error
  3795 ** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
  3796 ** can be used to restore the legacy behavior.
  3797 **
  3798 ** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
  3799 ** API always returns a generic error code, [SQLITE_ERROR], following any
  3800 ** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
  3801 ** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
  3802 ** specific [error codes] that better describes the error.
  3803 ** We admit that this is a goofy design.  The problem has been fixed
  3804 ** with the "v2" interface.  If you prepare all of your SQL statements
  3805 ** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
  3806 ** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
  3807 ** then the more specific [error codes] are returned directly
  3808 ** by sqlite3_step().  The use of the "v2" interface is recommended.
  3809 */
  3810 SQLITE_API int sqlite3_step(sqlite3_stmt*);
  3811 
  3812 /*
  3813 ** CAPI3REF: Number of columns in a result set
  3814 **
  3815 ** ^The sqlite3_data_count(P) interface returns the number of columns in the
  3816 ** current row of the result set of [prepared statement] P.
  3817 ** ^If prepared statement P does not have results ready to return
  3818 ** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
  3819 ** interfaces) then sqlite3_data_count(P) returns 0.
  3820 ** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
  3821 ** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
  3822 ** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
  3823 ** will return non-zero if previous call to [sqlite3_step](P) returned
  3824 ** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
  3825 ** where it always returns zero since each step of that multi-step
  3826 ** pragma returns 0 columns of data.
  3827 **
  3828 ** See also: [sqlite3_column_count()]
  3829 */
  3830 SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);
  3831 
  3832 /*
  3833 ** CAPI3REF: Fundamental Datatypes
  3834 ** KEYWORDS: SQLITE_TEXT
  3835 **
  3836 ** ^(Every value in SQLite has one of five fundamental datatypes:
  3837 **
  3838 ** <ul>
  3839 ** <li> 64-bit signed integer
  3840 ** <li> 64-bit IEEE floating point number
  3841 ** <li> string
  3842 ** <li> BLOB
  3843 ** <li> NULL
  3844 ** </ul>)^
  3845 **
  3846 ** These constants are codes for each of those types.
  3847 **
  3848 ** Note that the SQLITE_TEXT constant was also used in SQLite version 2
  3849 ** for a completely different meaning.  Software that links against both
  3850 ** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
  3851 ** SQLITE_TEXT.
  3852 */
  3853 #define SQLITE_INTEGER  1
  3854 #define SQLITE_FLOAT    2
  3855 #define SQLITE_BLOB     4
  3856 #define SQLITE_NULL     5
  3857 #ifdef SQLITE_TEXT
  3858 # undef SQLITE_TEXT
  3859 #else
  3860 # define SQLITE_TEXT     3
  3861 #endif
  3862 #define SQLITE3_TEXT     3
  3863 
  3864 /*
  3865 ** CAPI3REF: Result Values From A Query
  3866 ** KEYWORDS: {column access functions}
  3867 **
  3868 ** These routines form the "result set" interface.
  3869 **
  3870 ** ^These routines return information about a single column of the current
  3871 ** result row of a query.  ^In every case the first argument is a pointer
  3872 ** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
  3873 ** that was returned from [sqlite3_prepare_v2()] or one of its variants)
  3874 ** and the second argument is the index of the column for which information
  3875 ** should be returned. ^The leftmost column of the result set has the index 0.
  3876 ** ^The number of columns in the result can be determined using
  3877 ** [sqlite3_column_count()].
  3878 **
  3879 ** If the SQL statement does not currently point to a valid row, or if the
  3880 ** column index is out of range, the result is undefined.
  3881 ** These routines may only be called when the most recent call to
  3882 ** [sqlite3_step()] has returned [SQLITE_ROW] and neither
  3883 ** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
  3884 ** If any of these routines are called after [sqlite3_reset()] or
  3885 ** [sqlite3_finalize()] or after [sqlite3_step()] has returned
  3886 ** something other than [SQLITE_ROW], the results are undefined.
  3887 ** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
  3888 ** are called from a different thread while any of these routines
  3889 ** are pending, then the results are undefined.
  3890 **
  3891 ** ^The sqlite3_column_type() routine returns the
  3892 ** [SQLITE_INTEGER | datatype code] for the initial data type
  3893 ** of the result column.  ^The returned value is one of [SQLITE_INTEGER],
  3894 ** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
  3895 ** returned by sqlite3_column_type() is only meaningful if no type
  3896 ** conversions have occurred as described below.  After a type conversion,
  3897 ** the value returned by sqlite3_column_type() is undefined.  Future
  3898 ** versions of SQLite may change the behavior of sqlite3_column_type()
  3899 ** following a type conversion.
  3900 **
  3901 ** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
  3902 ** routine returns the number of bytes in that BLOB or string.
  3903 ** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
  3904 ** the string to UTF-8 and then returns the number of bytes.
  3905 ** ^If the result is a numeric value then sqlite3_column_bytes() uses
  3906 ** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
  3907 ** the number of bytes in that string.
  3908 ** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
  3909 **
  3910 ** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
  3911 ** routine returns the number of bytes in that BLOB or string.
  3912 ** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
  3913 ** the string to UTF-16 and then returns the number of bytes.
  3914 ** ^If the result is a numeric value then sqlite3_column_bytes16() uses
  3915 ** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
  3916 ** the number of bytes in that string.
  3917 ** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
  3918 **
  3919 ** ^The values returned by [sqlite3_column_bytes()] and 
  3920 ** [sqlite3_column_bytes16()] do not include the zero terminators at the end
  3921 ** of the string.  ^For clarity: the values returned by
  3922 ** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
  3923 ** bytes in the string, not the number of characters.
  3924 **
  3925 ** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
  3926 ** even empty strings, are always zero-terminated.  ^The return
  3927 ** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
  3928 **
  3929 ** ^The object returned by [sqlite3_column_value()] is an
  3930 ** [unprotected sqlite3_value] object.  An unprotected sqlite3_value object
  3931 ** may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()].
  3932 ** If the [unprotected sqlite3_value] object returned by
  3933 ** [sqlite3_column_value()] is used in any other way, including calls
  3934 ** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
  3935 ** or [sqlite3_value_bytes()], then the behavior is undefined.
  3936 **
  3937 ** These routines attempt to convert the value where appropriate.  ^For
  3938 ** example, if the internal representation is FLOAT and a text result
  3939 ** is requested, [sqlite3_snprintf()] is used internally to perform the
  3940 ** conversion automatically.  ^(The following table details the conversions
  3941 ** that are applied:
  3942 **
  3943 ** <blockquote>
  3944 ** <table border="1">
  3945 ** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
  3946 **
  3947 ** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
  3948 ** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
  3949 ** <tr><td>  NULL    <td>   TEXT    <td> Result is a NULL pointer
  3950 ** <tr><td>  NULL    <td>   BLOB    <td> Result is a NULL pointer
  3951 ** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
  3952 ** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
  3953 ** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
  3954 ** <tr><td>  FLOAT   <td> INTEGER   <td> [CAST] to INTEGER
  3955 ** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
  3956 ** <tr><td>  FLOAT   <td>   BLOB    <td> [CAST] to BLOB
  3957 ** <tr><td>  TEXT    <td> INTEGER   <td> [CAST] to INTEGER
  3958 ** <tr><td>  TEXT    <td>  FLOAT    <td> [CAST] to REAL
  3959 ** <tr><td>  TEXT    <td>   BLOB    <td> No change
  3960 ** <tr><td>  BLOB    <td> INTEGER   <td> [CAST] to INTEGER
  3961 ** <tr><td>  BLOB    <td>  FLOAT    <td> [CAST] to REAL
  3962 ** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
  3963 ** </table>
  3964 ** </blockquote>)^
  3965 **
  3966 ** The table above makes reference to standard C library functions atoi()
  3967 ** and atof().  SQLite does not really use these functions.  It has its
  3968 ** own equivalent internal routines.  The atoi() and atof() names are
  3969 ** used in the table for brevity and because they are familiar to most
  3970 ** C programmers.
  3971 **
  3972 ** Note that when type conversions occur, pointers returned by prior
  3973 ** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
  3974 ** sqlite3_column_text16() may be invalidated.
  3975 ** Type conversions and pointer invalidations might occur
  3976 ** in the following cases:
  3977 **
  3978 ** <ul>
  3979 ** <li> The initial content is a BLOB and sqlite3_column_text() or
  3980 **      sqlite3_column_text16() is called.  A zero-terminator might
  3981 **      need to be added to the string.</li>
  3982 ** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
  3983 **      sqlite3_column_text16() is called.  The content must be converted
  3984 **      to UTF-16.</li>
  3985 ** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
  3986 **      sqlite3_column_text() is called.  The content must be converted
  3987 **      to UTF-8.</li>
  3988 ** </ul>
  3989 **
  3990 ** ^Conversions between UTF-16be and UTF-16le are always done in place and do
  3991 ** not invalidate a prior pointer, though of course the content of the buffer
  3992 ** that the prior pointer references will have been modified.  Other kinds
  3993 ** of conversion are done in place when it is possible, but sometimes they
  3994 ** are not possible and in those cases prior pointers are invalidated.
  3995 **
  3996 ** The safest and easiest to remember policy is to invoke these routines
  3997 ** in one of the following ways:
  3998 **
  3999 ** <ul>
  4000 **  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
  4001 **  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
  4002 **  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
  4003 ** </ul>
  4004 **
  4005 ** In other words, you should call sqlite3_column_text(),
  4006 ** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
  4007 ** into the desired format, then invoke sqlite3_column_bytes() or
  4008 ** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
  4009 ** to sqlite3_column_text() or sqlite3_column_blob() with calls to
  4010 ** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
  4011 ** with calls to sqlite3_column_bytes().
  4012 **
  4013 ** ^The pointers returned are valid until a type conversion occurs as
  4014 ** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
  4015 ** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
  4016 ** and BLOBs is freed automatically.  Do <b>not</b> pass the pointers returned
  4017 ** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
  4018 ** [sqlite3_free()].
  4019 **
  4020 ** ^(If a memory allocation error occurs during the evaluation of any
  4021 ** of these routines, a default value is returned.  The default value
  4022 ** is either the integer 0, the floating point number 0.0, or a NULL
  4023 ** pointer.  Subsequent calls to [sqlite3_errcode()] will return
  4024 ** [SQLITE_NOMEM].)^
  4025 */
  4026 SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
  4027 SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
  4028 SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
  4029 SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
  4030 SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
  4031 SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
  4032 SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
  4033 SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
  4034 SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
  4035 SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
  4036 
  4037 /*
  4038 ** CAPI3REF: Destroy A Prepared Statement Object
  4039 **
  4040 ** ^The sqlite3_finalize() function is called to delete a [prepared statement].
  4041 ** ^If the most recent evaluation of the statement encountered no errors
  4042 ** or if the statement is never been evaluated, then sqlite3_finalize() returns
  4043 ** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
  4044 ** sqlite3_finalize(S) returns the appropriate [error code] or
  4045 ** [extended error code].
  4046 **
  4047 ** ^The sqlite3_finalize(S) routine can be called at any point during
  4048 ** the life cycle of [prepared statement] S:
  4049 ** before statement S is ever evaluated, after
  4050 ** one or more calls to [sqlite3_reset()], or after any call
  4051 ** to [sqlite3_step()] regardless of whether or not the statement has
  4052 ** completed execution.
  4053 **
  4054 ** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
  4055 **
  4056 ** The application must finalize every [prepared statement] in order to avoid
  4057 ** resource leaks.  It is a grievous error for the application to try to use
  4058 ** a prepared statement after it has been finalized.  Any use of a prepared
  4059 ** statement after it has been finalized can result in undefined and
  4060 ** undesirable behavior such as segfaults and heap corruption.
  4061 */
  4062 SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt);
  4063 
  4064 /*
  4065 ** CAPI3REF: Reset A Prepared Statement Object
  4066 **
  4067 ** The sqlite3_reset() function is called to reset a [prepared statement]
  4068 ** object back to its initial state, ready to be re-executed.
  4069 ** ^Any SQL statement variables that had values bound to them using
  4070 ** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
  4071 ** Use [sqlite3_clear_bindings()] to reset the bindings.
  4072 **
  4073 ** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
  4074 ** back to the beginning of its program.
  4075 **
  4076 ** ^If the most recent call to [sqlite3_step(S)] for the
  4077 ** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
  4078 ** or if [sqlite3_step(S)] has never before been called on S,
  4079 ** then [sqlite3_reset(S)] returns [SQLITE_OK].
  4080 **
  4081 ** ^If the most recent call to [sqlite3_step(S)] for the
  4082 ** [prepared statement] S indicated an error, then
  4083 ** [sqlite3_reset(S)] returns an appropriate [error code].
  4084 **
  4085 ** ^The [sqlite3_reset(S)] interface does not change the values
  4086 ** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
  4087 */
  4088 SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt);
  4089 
  4090 /*
  4091 ** CAPI3REF: Create Or Redefine SQL Functions
  4092 ** KEYWORDS: {function creation routines}
  4093 ** KEYWORDS: {application-defined SQL function}
  4094 ** KEYWORDS: {application-defined SQL functions}
  4095 **
  4096 ** ^These functions (collectively known as "function creation routines")
  4097 ** are used to add SQL functions or aggregates or to redefine the behavior
  4098 ** of existing SQL functions or aggregates.  The only differences between
  4099 ** these routines are the text encoding expected for
  4100 ** the second parameter (the name of the function being created)
  4101 ** and the presence or absence of a destructor callback for
  4102 ** the application data pointer.
  4103 **
  4104 ** ^The first parameter is the [database connection] to which the SQL
  4105 ** function is to be added.  ^If an application uses more than one database
  4106 ** connection then application-defined SQL functions must be added
  4107 ** to each database connection separately.
  4108 **
  4109 ** ^The second parameter is the name of the SQL function to be created or
  4110 ** redefined.  ^The length of the name is limited to 255 bytes in a UTF-8
  4111 ** representation, exclusive of the zero-terminator.  ^Note that the name
  4112 ** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.  
  4113 ** ^Any attempt to create a function with a longer name
  4114 ** will result in [SQLITE_MISUSE] being returned.
  4115 **
  4116 ** ^The third parameter (nArg)
  4117 ** is the number of arguments that the SQL function or
  4118 ** aggregate takes. ^If this parameter is -1, then the SQL function or
  4119 ** aggregate may take any number of arguments between 0 and the limit
  4120 ** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]).  If the third
  4121 ** parameter is less than -1 or greater than 127 then the behavior is
  4122 ** undefined.
  4123 **
  4124 ** ^The fourth parameter, eTextRep, specifies what
  4125 ** [SQLITE_UTF8 | text encoding] this SQL function prefers for
  4126 ** its parameters.  The application should set this parameter to
  4127 ** [SQLITE_UTF16LE] if the function implementation invokes 
  4128 ** [sqlite3_value_text16le()] on an input, or [SQLITE_UTF16BE] if the
  4129 ** implementation invokes [sqlite3_value_text16be()] on an input, or
  4130 ** [SQLITE_UTF16] if [sqlite3_value_text16()] is used, or [SQLITE_UTF8]
  4131 ** otherwise.  ^The same SQL function may be registered multiple times using
  4132 ** different preferred text encodings, with different implementations for
  4133 ** each encoding.
  4134 ** ^When multiple implementations of the same function are available, SQLite
  4135 ** will pick the one that involves the least amount of data conversion.
  4136 **
  4137 ** ^The fourth parameter may optionally be ORed with [SQLITE_DETERMINISTIC]
  4138 ** to signal that the function will always return the same result given
  4139 ** the same inputs within a single SQL statement.  Most SQL functions are
  4140 ** deterministic.  The built-in [random()] SQL function is an example of a
  4141 ** function that is not deterministic.  The SQLite query planner is able to
  4142 ** perform additional optimizations on deterministic functions, so use
  4143 ** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.
  4144 **
  4145 ** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
  4146 ** function can gain access to this pointer using [sqlite3_user_data()].)^
  4147 **
  4148 ** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
  4149 ** pointers to C-language functions that implement the SQL function or
  4150 ** aggregate. ^A scalar SQL function requires an implementation of the xFunc
  4151 ** callback only; NULL pointers must be passed as the xStep and xFinal
  4152 ** parameters. ^An aggregate SQL function requires an implementation of xStep
  4153 ** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
  4154 ** SQL function or aggregate, pass NULL pointers for all three function
  4155 ** callbacks.
  4156 **
  4157 ** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
  4158 ** then it is destructor for the application data pointer. 
  4159 ** The destructor is invoked when the function is deleted, either by being
  4160 ** overloaded or when the database connection closes.)^
  4161 ** ^The destructor is also invoked if the call to
  4162 ** sqlite3_create_function_v2() fails.
  4163 ** ^When the destructor callback of the tenth parameter is invoked, it
  4164 ** is passed a single argument which is a copy of the application data 
  4165 ** pointer which was the fifth parameter to sqlite3_create_function_v2().
  4166 **
  4167 ** ^It is permitted to register multiple implementations of the same
  4168 ** functions with the same name but with either differing numbers of
  4169 ** arguments or differing preferred text encodings.  ^SQLite will use
  4170 ** the implementation that most closely matches the way in which the
  4171 ** SQL function is used.  ^A function implementation with a non-negative
  4172 ** nArg parameter is a better match than a function implementation with
  4173 ** a negative nArg.  ^A function where the preferred text encoding
  4174 ** matches the database encoding is a better
  4175 ** match than a function where the encoding is different.  
  4176 ** ^A function where the encoding difference is between UTF16le and UTF16be
  4177 ** is a closer match than a function where the encoding difference is
  4178 ** between UTF8 and UTF16.
  4179 **
  4180 ** ^Built-in functions may be overloaded by new application-defined functions.
  4181 **
  4182 ** ^An application-defined function is permitted to call other
  4183 ** SQLite interfaces.  However, such calls must not
  4184 ** close the database connection nor finalize or reset the prepared
  4185 ** statement in which the function is running.
  4186 */
  4187 SQLITE_API int sqlite3_create_function(
  4188   sqlite3 *db,
  4189   const char *zFunctionName,
  4190   int nArg,
  4191   int eTextRep,
  4192   void *pApp,
  4193   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4194   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4195   void (*xFinal)(sqlite3_context*)
  4196 );
  4197 SQLITE_API int sqlite3_create_function16(
  4198   sqlite3 *db,
  4199   const void *zFunctionName,
  4200   int nArg,
  4201   int eTextRep,
  4202   void *pApp,
  4203   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4204   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4205   void (*xFinal)(sqlite3_context*)
  4206 );
  4207 SQLITE_API int sqlite3_create_function_v2(
  4208   sqlite3 *db,
  4209   const char *zFunctionName,
  4210   int nArg,
  4211   int eTextRep,
  4212   void *pApp,
  4213   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4214   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4215   void (*xFinal)(sqlite3_context*),
  4216   void(*xDestroy)(void*)
  4217 );
  4218 
  4219 /*
  4220 ** CAPI3REF: Text Encodings
  4221 **
  4222 ** These constant define integer codes that represent the various
  4223 ** text encodings supported by SQLite.
  4224 */
  4225 #define SQLITE_UTF8           1
  4226 #define SQLITE_UTF16LE        2
  4227 #define SQLITE_UTF16BE        3
  4228 #define SQLITE_UTF16          4    /* Use native byte order */
  4229 #define SQLITE_ANY            5    /* Deprecated */
  4230 #define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */
  4231 
  4232 /*
  4233 ** CAPI3REF: Function Flags
  4234 **
  4235 ** These constants may be ORed together with the 
  4236 ** [SQLITE_UTF8 | preferred text encoding] as the fourth argument
  4237 ** to [sqlite3_create_function()], [sqlite3_create_function16()], or
  4238 ** [sqlite3_create_function_v2()].
  4239 */
  4240 #define SQLITE_DETERMINISTIC    0x800
  4241 
  4242 /*
  4243 ** CAPI3REF: Deprecated Functions
  4244 ** DEPRECATED
  4245 **
  4246 ** These functions are [deprecated].  In order to maintain
  4247 ** backwards compatibility with older code, these functions continue 
  4248 ** to be supported.  However, new applications should avoid
  4249 ** the use of these functions.  To help encourage people to avoid
  4250 ** using these functions, we are not going to tell you what they do.
  4251 */
  4252 #ifndef SQLITE_OMIT_DEPRECATED
  4253 SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
  4254 SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
  4255 SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
  4256 SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
  4257 SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
  4258 SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
  4259                       void*,sqlite3_int64);
  4260 #endif
  4261 
  4262 /*
  4263 ** CAPI3REF: Obtaining SQL Function Parameter Values
  4264 **
  4265 ** The C-language implementation of SQL functions and aggregates uses
  4266 ** this set of interface routines to access the parameter values on
  4267 ** the function or aggregate.
  4268 **
  4269 ** The xFunc (for scalar functions) or xStep (for aggregates) parameters
  4270 ** to [sqlite3_create_function()] and [sqlite3_create_function16()]
  4271 ** define callbacks that implement the SQL functions and aggregates.
  4272 ** The 3rd parameter to these callbacks is an array of pointers to
  4273 ** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
  4274 ** each parameter to the SQL function.  These routines are used to
  4275 ** extract values from the [sqlite3_value] objects.
  4276 **
  4277 ** These routines work only with [protected sqlite3_value] objects.
  4278 ** Any attempt to use these routines on an [unprotected sqlite3_value]
  4279 ** object results in undefined behavior.
  4280 **
  4281 ** ^These routines work just like the corresponding [column access functions]
  4282 ** except that  these routines take a single [protected sqlite3_value] object
  4283 ** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
  4284 **
  4285 ** ^The sqlite3_value_text16() interface extracts a UTF-16 string
  4286 ** in the native byte-order of the host machine.  ^The
  4287 ** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
  4288 ** extract UTF-16 strings as big-endian and little-endian respectively.
  4289 **
  4290 ** ^(The sqlite3_value_numeric_type() interface attempts to apply
  4291 ** numeric affinity to the value.  This means that an attempt is
  4292 ** made to convert the value to an integer or floating point.  If
  4293 ** such a conversion is possible without loss of information (in other
  4294 ** words, if the value is a string that looks like a number)
  4295 ** then the conversion is performed.  Otherwise no conversion occurs.
  4296 ** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
  4297 **
  4298 ** Please pay particular attention to the fact that the pointer returned
  4299 ** from [sqlite3_value_blob()], [sqlite3_value_text()], or
  4300 ** [sqlite3_value_text16()] can be invalidated by a subsequent call to
  4301 ** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
  4302 ** or [sqlite3_value_text16()].
  4303 **
  4304 ** These routines must be called from the same thread as
  4305 ** the SQL function that supplied the [sqlite3_value*] parameters.
  4306 */
  4307 SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
  4308 SQLITE_API int sqlite3_value_bytes(sqlite3_value*);
  4309 SQLITE_API int sqlite3_value_bytes16(sqlite3_value*);
  4310 SQLITE_API double sqlite3_value_double(sqlite3_value*);
  4311 SQLITE_API int sqlite3_value_int(sqlite3_value*);
  4312 SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
  4313 SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
  4314 SQLITE_API const void *sqlite3_value_text16(sqlite3_value*);
  4315 SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*);
  4316 SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*);
  4317 SQLITE_API int sqlite3_value_type(sqlite3_value*);
  4318 SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*);
  4319 
  4320 /*
  4321 ** CAPI3REF: Obtain Aggregate Function Context
  4322 **
  4323 ** Implementations of aggregate SQL functions use this
  4324 ** routine to allocate memory for storing their state.
  4325 **
  4326 ** ^The first time the sqlite3_aggregate_context(C,N) routine is called 
  4327 ** for a particular aggregate function, SQLite
  4328 ** allocates N of memory, zeroes out that memory, and returns a pointer
  4329 ** to the new memory. ^On second and subsequent calls to
  4330 ** sqlite3_aggregate_context() for the same aggregate function instance,
  4331 ** the same buffer is returned.  Sqlite3_aggregate_context() is normally
  4332 ** called once for each invocation of the xStep callback and then one
  4333 ** last time when the xFinal callback is invoked.  ^(When no rows match
  4334 ** an aggregate query, the xStep() callback of the aggregate function
  4335 ** implementation is never called and xFinal() is called exactly once.
  4336 ** In those cases, sqlite3_aggregate_context() might be called for the
  4337 ** first time from within xFinal().)^
  4338 **
  4339 ** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer 
  4340 ** when first called if N is less than or equal to zero or if a memory
  4341 ** allocate error occurs.
  4342 **
  4343 ** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
  4344 ** determined by the N parameter on first successful call.  Changing the
  4345 ** value of N in subsequent call to sqlite3_aggregate_context() within
  4346 ** the same aggregate function instance will not resize the memory
  4347 ** allocation.)^  Within the xFinal callback, it is customary to set
  4348 ** N=0 in calls to sqlite3_aggregate_context(C,N) so that no 
  4349 ** pointless memory allocations occur.
  4350 **
  4351 ** ^SQLite automatically frees the memory allocated by 
  4352 ** sqlite3_aggregate_context() when the aggregate query concludes.
  4353 **
  4354 ** The first parameter must be a copy of the
  4355 ** [sqlite3_context | SQL function context] that is the first parameter
  4356 ** to the xStep or xFinal callback routine that implements the aggregate
  4357 ** function.
  4358 **
  4359 ** This routine must be called from the same thread in which
  4360 ** the aggregate SQL function is running.
  4361 */
  4362 SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);
  4363 
  4364 /*
  4365 ** CAPI3REF: User Data For Functions
  4366 **
  4367 ** ^The sqlite3_user_data() interface returns a copy of
  4368 ** the pointer that was the pUserData parameter (the 5th parameter)
  4369 ** of the [sqlite3_create_function()]
  4370 ** and [sqlite3_create_function16()] routines that originally
  4371 ** registered the application defined function.
  4372 **
  4373 ** This routine must be called from the same thread in which
  4374 ** the application-defined function is running.
  4375 */
  4376 SQLITE_API void *sqlite3_user_data(sqlite3_context*);
  4377 
  4378 /*
  4379 ** CAPI3REF: Database Connection For Functions
  4380 **
  4381 ** ^The sqlite3_context_db_handle() interface returns a copy of
  4382 ** the pointer to the [database connection] (the 1st parameter)
  4383 ** of the [sqlite3_create_function()]
  4384 ** and [sqlite3_create_function16()] routines that originally
  4385 ** registered the application defined function.
  4386 */
  4387 SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
  4388 
  4389 /*
  4390 ** CAPI3REF: Function Auxiliary Data
  4391 **
  4392 ** These functions may be used by (non-aggregate) SQL functions to
  4393 ** associate metadata with argument values. If the same value is passed to
  4394 ** multiple invocations of the same SQL function during query execution, under
  4395 ** some circumstances the associated metadata may be preserved.  An example
  4396 ** of where this might be useful is in a regular-expression matching
  4397 ** function. The compiled version of the regular expression can be stored as
  4398 ** metadata associated with the pattern string.  
  4399 ** Then as long as the pattern string remains the same,
  4400 ** the compiled regular expression can be reused on multiple
  4401 ** invocations of the same function.
  4402 **
  4403 ** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
  4404 ** associated by the sqlite3_set_auxdata() function with the Nth argument
  4405 ** value to the application-defined function. ^If there is no metadata
  4406 ** associated with the function argument, this sqlite3_get_auxdata() interface
  4407 ** returns a NULL pointer.
  4408 **
  4409 ** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
  4410 ** argument of the application-defined function.  ^Subsequent
  4411 ** calls to sqlite3_get_auxdata(C,N) return P from the most recent
  4412 ** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or
  4413 ** NULL if the metadata has been discarded.
  4414 ** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,
  4415 ** SQLite will invoke the destructor function X with parameter P exactly
  4416 ** once, when the metadata is discarded.
  4417 ** SQLite is free to discard the metadata at any time, including: <ul>
  4418 ** <li> when the corresponding function parameter changes, or
  4419 ** <li> when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
  4420 **      SQL statement, or
  4421 ** <li> when sqlite3_set_auxdata() is invoked again on the same parameter, or
  4422 ** <li> during the original sqlite3_set_auxdata() call when a memory 
  4423 **      allocation error occurs. </ul>)^
  4424 **
  4425 ** Note the last bullet in particular.  The destructor X in 
  4426 ** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
  4427 ** sqlite3_set_auxdata() interface even returns.  Hence sqlite3_set_auxdata()
  4428 ** should be called near the end of the function implementation and the
  4429 ** function implementation should not make any use of P after
  4430 ** sqlite3_set_auxdata() has been called.
  4431 **
  4432 ** ^(In practice, metadata is preserved between function calls for
  4433 ** function parameters that are compile-time constants, including literal
  4434 ** values and [parameters] and expressions composed from the same.)^
  4435 **
  4436 ** These routines must be called from the same thread in which
  4437 ** the SQL function is running.
  4438 */
  4439 SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N);
  4440 SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
  4441 
  4442 
  4443 /*
  4444 ** CAPI3REF: Constants Defining Special Destructor Behavior
  4445 **
  4446 ** These are special values for the destructor that is passed in as the
  4447 ** final argument to routines like [sqlite3_result_blob()].  ^If the destructor
  4448 ** argument is SQLITE_STATIC, it means that the content pointer is constant
  4449 ** and will never change.  It does not need to be destroyed.  ^The
  4450 ** SQLITE_TRANSIENT value means that the content will likely change in
  4451 ** the near future and that SQLite should make its own private copy of
  4452 ** the content before returning.
  4453 **
  4454 ** The typedef is necessary to work around problems in certain
  4455 ** C++ compilers.
  4456 */
  4457 typedef void (*sqlite3_destructor_type)(void*);
  4458 #define SQLITE_STATIC      ((sqlite3_destructor_type)0)
  4459 #define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)
  4460 
  4461 /*
  4462 ** CAPI3REF: Setting The Result Of An SQL Function
  4463 **
  4464 ** These routines are used by the xFunc or xFinal callbacks that
  4465 ** implement SQL functions and aggregates.  See
  4466 ** [sqlite3_create_function()] and [sqlite3_create_function16()]
  4467 ** for additional information.
  4468 **
  4469 ** These functions work very much like the [parameter binding] family of
  4470 ** functions used to bind values to host parameters in prepared statements.
  4471 ** Refer to the [SQL parameter] documentation for additional information.
  4472 **
  4473 ** ^The sqlite3_result_blob() interface sets the result from
  4474 ** an application-defined function to be the BLOB whose content is pointed
  4475 ** to by the second parameter and which is N bytes long where N is the
  4476 ** third parameter.
  4477 **
  4478 ** ^The sqlite3_result_zeroblob() interfaces set the result of
  4479 ** the application-defined function to be a BLOB containing all zero
  4480 ** bytes and N bytes in size, where N is the value of the 2nd parameter.
  4481 **
  4482 ** ^The sqlite3_result_double() interface sets the result from
  4483 ** an application-defined function to be a floating point value specified
  4484 ** by its 2nd argument.
  4485 **
  4486 ** ^The sqlite3_result_error() and sqlite3_result_error16() functions
  4487 ** cause the implemented SQL function to throw an exception.
  4488 ** ^SQLite uses the string pointed to by the
  4489 ** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
  4490 ** as the text of an error message.  ^SQLite interprets the error
  4491 ** message string from sqlite3_result_error() as UTF-8. ^SQLite
  4492 ** interprets the string from sqlite3_result_error16() as UTF-16 in native
  4493 ** byte order.  ^If the third parameter to sqlite3_result_error()
  4494 ** or sqlite3_result_error16() is negative then SQLite takes as the error
  4495 ** message all text up through the first zero character.
  4496 ** ^If the third parameter to sqlite3_result_error() or
  4497 ** sqlite3_result_error16() is non-negative then SQLite takes that many
  4498 ** bytes (not characters) from the 2nd parameter as the error message.
  4499 ** ^The sqlite3_result_error() and sqlite3_result_error16()
  4500 ** routines make a private copy of the error message text before
  4501 ** they return.  Hence, the calling function can deallocate or
  4502 ** modify the text after they return without harm.
  4503 ** ^The sqlite3_result_error_code() function changes the error code
  4504 ** returned by SQLite as a result of an error in a function.  ^By default,
  4505 ** the error code is SQLITE_ERROR.  ^A subsequent call to sqlite3_result_error()
  4506 ** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
  4507 **
  4508 ** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an
  4509 ** error indicating that a string or BLOB is too long to represent.
  4510 **
  4511 ** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an
  4512 ** error indicating that a memory allocation failed.
  4513 **
  4514 ** ^The sqlite3_result_int() interface sets the return value
  4515 ** of the application-defined function to be the 32-bit signed integer
  4516 ** value given in the 2nd argument.
  4517 ** ^The sqlite3_result_int64() interface sets the return value
  4518 ** of the application-defined function to be the 64-bit signed integer
  4519 ** value given in the 2nd argument.
  4520 **
  4521 ** ^The sqlite3_result_null() interface sets the return value
  4522 ** of the application-defined function to be NULL.
  4523 **
  4524 ** ^The sqlite3_result_text(), sqlite3_result_text16(),
  4525 ** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
  4526 ** set the return value of the application-defined function to be
  4527 ** a text string which is represented as UTF-8, UTF-16 native byte order,
  4528 ** UTF-16 little endian, or UTF-16 big endian, respectively.
  4529 ** ^SQLite takes the text result from the application from
  4530 ** the 2nd parameter of the sqlite3_result_text* interfaces.
  4531 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  4532 ** is negative, then SQLite takes result text from the 2nd parameter
  4533 ** through the first zero character.
  4534 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  4535 ** is non-negative, then as many bytes (not characters) of the text
  4536 ** pointed to by the 2nd parameter are taken as the application-defined
  4537 ** function result.  If the 3rd parameter is non-negative, then it
  4538 ** must be the byte offset into the string where the NUL terminator would
  4539 ** appear if the string where NUL terminated.  If any NUL characters occur
  4540 ** in the string at a byte offset that is less than the value of the 3rd
  4541 ** parameter, then the resulting string will contain embedded NULs and the
  4542 ** result of expressions operating on strings with embedded NULs is undefined.
  4543 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  4544 ** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
  4545 ** function as the destructor on the text or BLOB result when it has
  4546 ** finished using that result.
  4547 ** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
  4548 ** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
  4549 ** assumes that the text or BLOB result is in constant space and does not
  4550 ** copy the content of the parameter nor call a destructor on the content
  4551 ** when it has finished using that result.
  4552 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  4553 ** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
  4554 ** then SQLite makes a copy of the result into space obtained from
  4555 ** from [sqlite3_malloc()] before it returns.
  4556 **
  4557 ** ^The sqlite3_result_value() interface sets the result of
  4558 ** the application-defined function to be a copy the
  4559 ** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
  4560 ** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
  4561 ** so that the [sqlite3_value] specified in the parameter may change or
  4562 ** be deallocated after sqlite3_result_value() returns without harm.
  4563 ** ^A [protected sqlite3_value] object may always be used where an
  4564 ** [unprotected sqlite3_value] object is required, so either
  4565 ** kind of [sqlite3_value] object can be used with this interface.
  4566 **
  4567 ** If these routines are called from within the different thread
  4568 ** than the one containing the application-defined function that received
  4569 ** the [sqlite3_context] pointer, the results are undefined.
  4570 */
  4571 SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
  4572 SQLITE_API void sqlite3_result_double(sqlite3_context*, double);
  4573 SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
  4574 SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
  4575 SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*);
  4576 SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*);
  4577 SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int);
  4578 SQLITE_API void sqlite3_result_int(sqlite3_context*, int);
  4579 SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
  4580 SQLITE_API void sqlite3_result_null(sqlite3_context*);
  4581 SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
  4582 SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
  4583 SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
  4584 SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
  4585 SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
  4586 SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n);
  4587 
  4588 /*
  4589 ** CAPI3REF: Define New Collating Sequences
  4590 **
  4591 ** ^These functions add, remove, or modify a [collation] associated
  4592 ** with the [database connection] specified as the first argument.
  4593 **
  4594 ** ^The name of the collation is a UTF-8 string
  4595 ** for sqlite3_create_collation() and sqlite3_create_collation_v2()
  4596 ** and a UTF-16 string in native byte order for sqlite3_create_collation16().
  4597 ** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
  4598 ** considered to be the same name.
  4599 **
  4600 ** ^(The third argument (eTextRep) must be one of the constants:
  4601 ** <ul>
  4602 ** <li> [SQLITE_UTF8],
  4603 ** <li> [SQLITE_UTF16LE],
  4604 ** <li> [SQLITE_UTF16BE],
  4605 ** <li> [SQLITE_UTF16], or
  4606 ** <li> [SQLITE_UTF16_ALIGNED].
  4607 ** </ul>)^
  4608 ** ^The eTextRep argument determines the encoding of strings passed
  4609 ** to the collating function callback, xCallback.
  4610 ** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
  4611 ** force strings to be UTF16 with native byte order.
  4612 ** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
  4613 ** on an even byte address.
  4614 **
  4615 ** ^The fourth argument, pArg, is an application data pointer that is passed
  4616 ** through as the first argument to the collating function callback.
  4617 **
  4618 ** ^The fifth argument, xCallback, is a pointer to the collating function.
  4619 ** ^Multiple collating functions can be registered using the same name but
  4620 ** with different eTextRep parameters and SQLite will use whichever
  4621 ** function requires the least amount of data transformation.
  4622 ** ^If the xCallback argument is NULL then the collating function is
  4623 ** deleted.  ^When all collating functions having the same name are deleted,
  4624 ** that collation is no longer usable.
  4625 **
  4626 ** ^The collating function callback is invoked with a copy of the pArg 
  4627 ** application data pointer and with two strings in the encoding specified
  4628 ** by the eTextRep argument.  The collating function must return an
  4629 ** integer that is negative, zero, or positive
  4630 ** if the first string is less than, equal to, or greater than the second,
  4631 ** respectively.  A collating function must always return the same answer
  4632 ** given the same inputs.  If two or more collating functions are registered
  4633 ** to the same collation name (using different eTextRep values) then all
  4634 ** must give an equivalent answer when invoked with equivalent strings.
  4635 ** The collating function must obey the following properties for all
  4636 ** strings A, B, and C:
  4637 **
  4638 ** <ol>
  4639 ** <li> If A==B then B==A.
  4640 ** <li> If A==B and B==C then A==C.
  4641 ** <li> If A&lt;B THEN B&gt;A.
  4642 ** <li> If A&lt;B and B&lt;C then A&lt;C.
  4643 ** </ol>
  4644 **
  4645 ** If a collating function fails any of the above constraints and that
  4646 ** collating function is  registered and used, then the behavior of SQLite
  4647 ** is undefined.
  4648 **
  4649 ** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
  4650 ** with the addition that the xDestroy callback is invoked on pArg when
  4651 ** the collating function is deleted.
  4652 ** ^Collating functions are deleted when they are overridden by later
  4653 ** calls to the collation creation functions or when the
  4654 ** [database connection] is closed using [sqlite3_close()].
  4655 **
  4656 ** ^The xDestroy callback is <u>not</u> called if the 
  4657 ** sqlite3_create_collation_v2() function fails.  Applications that invoke
  4658 ** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should 
  4659 ** check the return code and dispose of the application data pointer
  4660 ** themselves rather than expecting SQLite to deal with it for them.
  4661 ** This is different from every other SQLite interface.  The inconsistency 
  4662 ** is unfortunate but cannot be changed without breaking backwards 
  4663 ** compatibility.
  4664 **
  4665 ** See also:  [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
  4666 */
  4667 SQLITE_API int sqlite3_create_collation(
  4668   sqlite3*, 
  4669   const char *zName, 
  4670   int eTextRep, 
  4671   void *pArg,
  4672   int(*xCompare)(void*,int,const void*,int,const void*)
  4673 );
  4674 SQLITE_API int sqlite3_create_collation_v2(
  4675   sqlite3*, 
  4676   const char *zName, 
  4677   int eTextRep, 
  4678   void *pArg,
  4679   int(*xCompare)(void*,int,const void*,int,const void*),
  4680   void(*xDestroy)(void*)
  4681 );
  4682 SQLITE_API int sqlite3_create_collation16(
  4683   sqlite3*, 
  4684   const void *zName,
  4685   int eTextRep, 
  4686   void *pArg,
  4687   int(*xCompare)(void*,int,const void*,int,const void*)
  4688 );
  4689 
  4690 /*
  4691 ** CAPI3REF: Collation Needed Callbacks
  4692 **
  4693 ** ^To avoid having to register all collation sequences before a database
  4694 ** can be used, a single callback function may be registered with the
  4695 ** [database connection] to be invoked whenever an undefined collation
  4696 ** sequence is required.
  4697 **
  4698 ** ^If the function is registered using the sqlite3_collation_needed() API,
  4699 ** then it is passed the names of undefined collation sequences as strings
  4700 ** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
  4701 ** the names are passed as UTF-16 in machine native byte order.
  4702 ** ^A call to either function replaces the existing collation-needed callback.
  4703 **
  4704 ** ^(When the callback is invoked, the first argument passed is a copy
  4705 ** of the second argument to sqlite3_collation_needed() or
  4706 ** sqlite3_collation_needed16().  The second argument is the database
  4707 ** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
  4708 ** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
  4709 ** sequence function required.  The fourth parameter is the name of the
  4710 ** required collation sequence.)^
  4711 **
  4712 ** The callback function should register the desired collation using
  4713 ** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
  4714 ** [sqlite3_create_collation_v2()].
  4715 */
  4716 SQLITE_API int sqlite3_collation_needed(
  4717   sqlite3*, 
  4718   void*, 
  4719   void(*)(void*,sqlite3*,int eTextRep,const char*)
  4720 );
  4721 SQLITE_API int sqlite3_collation_needed16(
  4722   sqlite3*, 
  4723   void*,
  4724   void(*)(void*,sqlite3*,int eTextRep,const void*)
  4725 );
  4726 
  4727 #ifdef SQLITE_HAS_CODEC
  4728 /*
  4729 ** Specify the key for an encrypted database.  This routine should be
  4730 ** called right after sqlite3_open().
  4731 **
  4732 ** The code to implement this API is not available in the public release
  4733 ** of SQLite.
  4734 */
  4735 SQLITE_API int sqlite3_key(
  4736   sqlite3 *db,                   /* Database to be rekeyed */
  4737   const void *pKey, int nKey     /* The key */
  4738 );
  4739 SQLITE_API int sqlite3_key_v2(
  4740   sqlite3 *db,                   /* Database to be rekeyed */
  4741   const char *zDbName,           /* Name of the database */
  4742   const void *pKey, int nKey     /* The key */
  4743 );
  4744 
  4745 /*
  4746 ** Change the key on an open database.  If the current database is not
  4747 ** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
  4748 ** database is decrypted.
  4749 **
  4750 ** The code to implement this API is not available in the public release
  4751 ** of SQLite.
  4752 */
  4753 SQLITE_API int sqlite3_rekey(
  4754   sqlite3 *db,                   /* Database to be rekeyed */
  4755   const void *pKey, int nKey     /* The new key */
  4756 );
  4757 SQLITE_API int sqlite3_rekey_v2(
  4758   sqlite3 *db,                   /* Database to be rekeyed */
  4759   const char *zDbName,           /* Name of the database */
  4760   const void *pKey, int nKey     /* The new key */
  4761 );
  4762 
  4763 /*
  4764 ** Specify the activation key for a SEE database.  Unless 
  4765 ** activated, none of the SEE routines will work.
  4766 */
  4767 SQLITE_API void sqlite3_activate_see(
  4768   const char *zPassPhrase        /* Activation phrase */
  4769 );
  4770 #endif
  4771 
  4772 #ifdef SQLITE_ENABLE_CEROD
  4773 /*
  4774 ** Specify the activation key for a CEROD database.  Unless 
  4775 ** activated, none of the CEROD routines will work.
  4776 */
  4777 SQLITE_API void sqlite3_activate_cerod(
  4778   const char *zPassPhrase        /* Activation phrase */
  4779 );
  4780 #endif
  4781 
  4782 /*
  4783 ** CAPI3REF: Suspend Execution For A Short Time
  4784 **
  4785 ** The sqlite3_sleep() function causes the current thread to suspend execution
  4786 ** for at least a number of milliseconds specified in its parameter.
  4787 **
  4788 ** If the operating system does not support sleep requests with
  4789 ** millisecond time resolution, then the time will be rounded up to
  4790 ** the nearest second. The number of milliseconds of sleep actually
  4791 ** requested from the operating system is returned.
  4792 **
  4793 ** ^SQLite implements this interface by calling the xSleep()
  4794 ** method of the default [sqlite3_vfs] object.  If the xSleep() method
  4795 ** of the default VFS is not implemented correctly, or not implemented at
  4796 ** all, then the behavior of sqlite3_sleep() may deviate from the description
  4797 ** in the previous paragraphs.
  4798 */
  4799 SQLITE_API int sqlite3_sleep(int);
  4800 
  4801 /*
  4802 ** CAPI3REF: Name Of The Folder Holding Temporary Files
  4803 **
  4804 ** ^(If this global variable is made to point to a string which is
  4805 ** the name of a folder (a.k.a. directory), then all temporary files
  4806 ** created by SQLite when using a built-in [sqlite3_vfs | VFS]
  4807 ** will be placed in that directory.)^  ^If this variable
  4808 ** is a NULL pointer, then SQLite performs a search for an appropriate
  4809 ** temporary file directory.
  4810 **
  4811 ** Applications are strongly discouraged from using this global variable.
  4812 ** It is required to set a temporary folder on Windows Runtime (WinRT).
  4813 ** But for all other platforms, it is highly recommended that applications
  4814 ** neither read nor write this variable.  This global variable is a relic
  4815 ** that exists for backwards compatibility of legacy applications and should
  4816 ** be avoided in new projects.
  4817 **
  4818 ** It is not safe to read or modify this variable in more than one
  4819 ** thread at a time.  It is not safe to read or modify this variable
  4820 ** if a [database connection] is being used at the same time in a separate
  4821 ** thread.
  4822 ** It is intended that this variable be set once
  4823 ** as part of process initialization and before any SQLite interface
  4824 ** routines have been called and that this variable remain unchanged
  4825 ** thereafter.
  4826 **
  4827 ** ^The [temp_store_directory pragma] may modify this variable and cause
  4828 ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  4829 ** the [temp_store_directory pragma] always assumes that any string
  4830 ** that this variable points to is held in memory obtained from 
  4831 ** [sqlite3_malloc] and the pragma may attempt to free that memory
  4832 ** using [sqlite3_free].
  4833 ** Hence, if this variable is modified directly, either it should be
  4834 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  4835 ** or else the use of the [temp_store_directory pragma] should be avoided.
  4836 ** Except when requested by the [temp_store_directory pragma], SQLite
  4837 ** does not free the memory that sqlite3_temp_directory points to.  If
  4838 ** the application wants that memory to be freed, it must do
  4839 ** so itself, taking care to only do so after all [database connection]
  4840 ** objects have been destroyed.
  4841 **
  4842 ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  4843 ** prior to calling [sqlite3_open] or [sqlite3_open_v2].  Otherwise, various
  4844 ** features that require the use of temporary files may fail.  Here is an
  4845 ** example of how to do this using C++ with the Windows Runtime:
  4846 **
  4847 ** <blockquote><pre>
  4848 ** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->
  4849 ** &nbsp;     TemporaryFolder->Path->Data();
  4850 ** char zPathBuf&#91;MAX_PATH + 1&#93;;
  4851 ** memset(zPathBuf, 0, sizeof(zPathBuf));
  4852 ** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),
  4853 ** &nbsp;     NULL, NULL);
  4854 ** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);
  4855 ** </pre></blockquote>
  4856 */
  4857 SQLITE_API char *sqlite3_temp_directory;
  4858 
  4859 /*
  4860 ** CAPI3REF: Name Of The Folder Holding Database Files
  4861 **
  4862 ** ^(If this global variable is made to point to a string which is
  4863 ** the name of a folder (a.k.a. directory), then all database files
  4864 ** specified with a relative pathname and created or accessed by
  4865 ** SQLite when using a built-in windows [sqlite3_vfs | VFS] will be assumed
  4866 ** to be relative to that directory.)^ ^If this variable is a NULL
  4867 ** pointer, then SQLite assumes that all database files specified
  4868 ** with a relative pathname are relative to the current directory
  4869 ** for the process.  Only the windows VFS makes use of this global
  4870 ** variable; it is ignored by the unix VFS.
  4871 **
  4872 ** Changing the value of this variable while a database connection is
  4873 ** open can result in a corrupt database.
  4874 **
  4875 ** It is not safe to read or modify this variable in more than one
  4876 ** thread at a time.  It is not safe to read or modify this variable
  4877 ** if a [database connection] is being used at the same time in a separate
  4878 ** thread.
  4879 ** It is intended that this variable be set once
  4880 ** as part of process initialization and before any SQLite interface
  4881 ** routines have been called and that this variable remain unchanged
  4882 ** thereafter.
  4883 **
  4884 ** ^The [data_store_directory pragma] may modify this variable and cause
  4885 ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  4886 ** the [data_store_directory pragma] always assumes that any string
  4887 ** that this variable points to is held in memory obtained from 
  4888 ** [sqlite3_malloc] and the pragma may attempt to free that memory
  4889 ** using [sqlite3_free].
  4890 ** Hence, if this variable is modified directly, either it should be
  4891 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  4892 ** or else the use of the [data_store_directory pragma] should be avoided.
  4893 */
  4894 SQLITE_API char *sqlite3_data_directory;
  4895 
  4896 /*
  4897 ** CAPI3REF: Test For Auto-Commit Mode
  4898 ** KEYWORDS: {autocommit mode}
  4899 **
  4900 ** ^The sqlite3_get_autocommit() interface returns non-zero or
  4901 ** zero if the given database connection is or is not in autocommit mode,
  4902 ** respectively.  ^Autocommit mode is on by default.
  4903 ** ^Autocommit mode is disabled by a [BEGIN] statement.
  4904 ** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
  4905 **
  4906 ** If certain kinds of errors occur on a statement within a multi-statement
  4907 ** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
  4908 ** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
  4909 ** transaction might be rolled back automatically.  The only way to
  4910 ** find out whether SQLite automatically rolled back the transaction after
  4911 ** an error is to use this function.
  4912 **
  4913 ** If another thread changes the autocommit status of the database
  4914 ** connection while this routine is running, then the return value
  4915 ** is undefined.
  4916 */
  4917 SQLITE_API int sqlite3_get_autocommit(sqlite3*);
  4918 
  4919 /*
  4920 ** CAPI3REF: Find The Database Handle Of A Prepared Statement
  4921 **
  4922 ** ^The sqlite3_db_handle interface returns the [database connection] handle
  4923 ** to which a [prepared statement] belongs.  ^The [database connection]
  4924 ** returned by sqlite3_db_handle is the same [database connection]
  4925 ** that was the first argument
  4926 ** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
  4927 ** create the statement in the first place.
  4928 */
  4929 SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
  4930 
  4931 /*
  4932 ** CAPI3REF: Return The Filename For A Database Connection
  4933 **
  4934 ** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
  4935 ** associated with database N of connection D.  ^The main database file
  4936 ** has the name "main".  If there is no attached database N on the database
  4937 ** connection D, or if database N is a temporary or in-memory database, then
  4938 ** a NULL pointer is returned.
  4939 **
  4940 ** ^The filename returned by this function is the output of the
  4941 ** xFullPathname method of the [VFS].  ^In other words, the filename
  4942 ** will be an absolute pathname, even if the filename used
  4943 ** to open the database originally was a URI or relative pathname.
  4944 */
  4945 SQLITE_API const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
  4946 
  4947 /*
  4948 ** CAPI3REF: Determine if a database is read-only
  4949 **
  4950 ** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N
  4951 ** of connection D is read-only, 0 if it is read/write, or -1 if N is not
  4952 ** the name of a database on connection D.
  4953 */
  4954 SQLITE_API int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
  4955 
  4956 /*
  4957 ** CAPI3REF: Find the next prepared statement
  4958 **
  4959 ** ^This interface returns a pointer to the next [prepared statement] after
  4960 ** pStmt associated with the [database connection] pDb.  ^If pStmt is NULL
  4961 ** then this interface returns a pointer to the first prepared statement
  4962 ** associated with the database connection pDb.  ^If no prepared statement
  4963 ** satisfies the conditions of this routine, it returns NULL.
  4964 **
  4965 ** The [database connection] pointer D in a call to
  4966 ** [sqlite3_next_stmt(D,S)] must refer to an open database
  4967 ** connection and in particular must not be a NULL pointer.
  4968 */
  4969 SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
  4970 
  4971 /*
  4972 ** CAPI3REF: Commit And Rollback Notification Callbacks
  4973 **
  4974 ** ^The sqlite3_commit_hook() interface registers a callback
  4975 ** function to be invoked whenever a transaction is [COMMIT | committed].
  4976 ** ^Any callback set by a previous call to sqlite3_commit_hook()
  4977 ** for the same database connection is overridden.
  4978 ** ^The sqlite3_rollback_hook() interface registers a callback
  4979 ** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
  4980 ** ^Any callback set by a previous call to sqlite3_rollback_hook()
  4981 ** for the same database connection is overridden.
  4982 ** ^The pArg argument is passed through to the callback.
  4983 ** ^If the callback on a commit hook function returns non-zero,
  4984 ** then the commit is converted into a rollback.
  4985 **
  4986 ** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
  4987 ** return the P argument from the previous call of the same function
  4988 ** on the same [database connection] D, or NULL for
  4989 ** the first call for each function on D.
  4990 **
  4991 ** The commit and rollback hook callbacks are not reentrant.
  4992 ** The callback implementation must not do anything that will modify
  4993 ** the database connection that invoked the callback.  Any actions
  4994 ** to modify the database connection must be deferred until after the
  4995 ** completion of the [sqlite3_step()] call that triggered the commit
  4996 ** or rollback hook in the first place.
  4997 ** Note that running any other SQL statements, including SELECT statements,
  4998 ** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
  4999 ** the database connections for the meaning of "modify" in this paragraph.
  5000 **
  5001 ** ^Registering a NULL function disables the callback.
  5002 **
  5003 ** ^When the commit hook callback routine returns zero, the [COMMIT]
  5004 ** operation is allowed to continue normally.  ^If the commit hook
  5005 ** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
  5006 ** ^The rollback hook is invoked on a rollback that results from a commit
  5007 ** hook returning non-zero, just as it would be with any other rollback.
  5008 **
  5009 ** ^For the purposes of this API, a transaction is said to have been
  5010 ** rolled back if an explicit "ROLLBACK" statement is executed, or
  5011 ** an error or constraint causes an implicit rollback to occur.
  5012 ** ^The rollback callback is not invoked if a transaction is
  5013 ** automatically rolled back because the database connection is closed.
  5014 **
  5015 ** See also the [sqlite3_update_hook()] interface.
  5016 */
  5017 SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
  5018 SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
  5019 
  5020 /*
  5021 ** CAPI3REF: Data Change Notification Callbacks
  5022 **
  5023 ** ^The sqlite3_update_hook() interface registers a callback function
  5024 ** with the [database connection] identified by the first argument
  5025 ** to be invoked whenever a row is updated, inserted or deleted in
  5026 ** a rowid table.
  5027 ** ^Any callback set by a previous call to this function
  5028 ** for the same database connection is overridden.
  5029 **
  5030 ** ^The second argument is a pointer to the function to invoke when a
  5031 ** row is updated, inserted or deleted in a rowid table.
  5032 ** ^The first argument to the callback is a copy of the third argument
  5033 ** to sqlite3_update_hook().
  5034 ** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
  5035 ** or [SQLITE_UPDATE], depending on the operation that caused the callback
  5036 ** to be invoked.
  5037 ** ^The third and fourth arguments to the callback contain pointers to the
  5038 ** database and table name containing the affected row.
  5039 ** ^The final callback parameter is the [rowid] of the row.
  5040 ** ^In the case of an update, this is the [rowid] after the update takes place.
  5041 **
  5042 ** ^(The update hook is not invoked when internal system tables are
  5043 ** modified (i.e. sqlite_master and sqlite_sequence).)^
  5044 ** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.
  5045 **
  5046 ** ^In the current implementation, the update hook
  5047 ** is not invoked when duplication rows are deleted because of an
  5048 ** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
  5049 ** invoked when rows are deleted using the [truncate optimization].
  5050 ** The exceptions defined in this paragraph might change in a future
  5051 ** release of SQLite.
  5052 **
  5053 ** The update hook implementation must not do anything that will modify
  5054 ** the database connection that invoked the update hook.  Any actions
  5055 ** to modify the database connection must be deferred until after the
  5056 ** completion of the [sqlite3_step()] call that triggered the update hook.
  5057 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  5058 ** database connections for the meaning of "modify" in this paragraph.
  5059 **
  5060 ** ^The sqlite3_update_hook(D,C,P) function
  5061 ** returns the P argument from the previous call
  5062 ** on the same [database connection] D, or NULL for
  5063 ** the first call on D.
  5064 **
  5065 ** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]
  5066 ** interfaces.
  5067 */
  5068 SQLITE_API void *sqlite3_update_hook(
  5069   sqlite3*, 
  5070   void(*)(void *,int ,char const *,char const *,sqlite3_int64),
  5071   void*
  5072 );
  5073 
  5074 /*
  5075 ** CAPI3REF: Enable Or Disable Shared Pager Cache
  5076 **
  5077 ** ^(This routine enables or disables the sharing of the database cache
  5078 ** and schema data structures between [database connection | connections]
  5079 ** to the same database. Sharing is enabled if the argument is true
  5080 ** and disabled if the argument is false.)^
  5081 **
  5082 ** ^Cache sharing is enabled and disabled for an entire process.
  5083 ** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
  5084 ** sharing was enabled or disabled for each thread separately.
  5085 **
  5086 ** ^(The cache sharing mode set by this interface effects all subsequent
  5087 ** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
  5088 ** Existing database connections continue use the sharing mode
  5089 ** that was in effect at the time they were opened.)^
  5090 **
  5091 ** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
  5092 ** successfully.  An [error code] is returned otherwise.)^
  5093 **
  5094 ** ^Shared cache is disabled by default. But this might change in
  5095 ** future releases of SQLite.  Applications that care about shared
  5096 ** cache setting should set it explicitly.
  5097 **
  5098 ** This interface is threadsafe on processors where writing a
  5099 ** 32-bit integer is atomic.
  5100 **
  5101 ** See Also:  [SQLite Shared-Cache Mode]
  5102 */
  5103 SQLITE_API int sqlite3_enable_shared_cache(int);
  5104 
  5105 /*
  5106 ** CAPI3REF: Attempt To Free Heap Memory
  5107 **
  5108 ** ^The sqlite3_release_memory() interface attempts to free N bytes
  5109 ** of heap memory by deallocating non-essential memory allocations
  5110 ** held by the database library.   Memory used to cache database
  5111 ** pages to improve performance is an example of non-essential memory.
  5112 ** ^sqlite3_release_memory() returns the number of bytes actually freed,
  5113 ** which might be more or less than the amount requested.
  5114 ** ^The sqlite3_release_memory() routine is a no-op returning zero
  5115 ** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  5116 **
  5117 ** See also: [sqlite3_db_release_memory()]
  5118 */
  5119 SQLITE_API int sqlite3_release_memory(int);
  5120 
  5121 /*
  5122 ** CAPI3REF: Free Memory Used By A Database Connection
  5123 **
  5124 ** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
  5125 ** memory as possible from database connection D. Unlike the
  5126 ** [sqlite3_release_memory()] interface, this interface is in effect even
  5127 ** when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
  5128 ** omitted.
  5129 **
  5130 ** See also: [sqlite3_release_memory()]
  5131 */
  5132 SQLITE_API int sqlite3_db_release_memory(sqlite3*);
  5133 
  5134 /*
  5135 ** CAPI3REF: Impose A Limit On Heap Size
  5136 **
  5137 ** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
  5138 ** soft limit on the amount of heap memory that may be allocated by SQLite.
  5139 ** ^SQLite strives to keep heap memory utilization below the soft heap
  5140 ** limit by reducing the number of pages held in the page cache
  5141 ** as heap memory usages approaches the limit.
  5142 ** ^The soft heap limit is "soft" because even though SQLite strives to stay
  5143 ** below the limit, it will exceed the limit rather than generate
  5144 ** an [SQLITE_NOMEM] error.  In other words, the soft heap limit 
  5145 ** is advisory only.
  5146 **
  5147 ** ^The return value from sqlite3_soft_heap_limit64() is the size of
  5148 ** the soft heap limit prior to the call, or negative in the case of an
  5149 ** error.  ^If the argument N is negative
  5150 ** then no change is made to the soft heap limit.  Hence, the current
  5151 ** size of the soft heap limit can be determined by invoking
  5152 ** sqlite3_soft_heap_limit64() with a negative argument.
  5153 **
  5154 ** ^If the argument N is zero then the soft heap limit is disabled.
  5155 **
  5156 ** ^(The soft heap limit is not enforced in the current implementation
  5157 ** if one or more of following conditions are true:
  5158 **
  5159 ** <ul>
  5160 ** <li> The soft heap limit is set to zero.
  5161 ** <li> Memory accounting is disabled using a combination of the
  5162 **      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
  5163 **      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
  5164 ** <li> An alternative page cache implementation is specified using
  5165 **      [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).
  5166 ** <li> The page cache allocates from its own memory pool supplied
  5167 **      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
  5168 **      from the heap.
  5169 ** </ul>)^
  5170 **
  5171 ** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
  5172 ** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
  5173 ** compile-time option is invoked.  With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
  5174 ** the soft heap limit is enforced on every memory allocation.  Without
  5175 ** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
  5176 ** when memory is allocated by the page cache.  Testing suggests that because
  5177 ** the page cache is the predominate memory user in SQLite, most
  5178 ** applications will achieve adequate soft heap limit enforcement without
  5179 ** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  5180 **
  5181 ** The circumstances under which SQLite will enforce the soft heap limit may
  5182 ** changes in future releases of SQLite.
  5183 */
  5184 SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);
  5185 
  5186 /*
  5187 ** CAPI3REF: Deprecated Soft Heap Limit Interface
  5188 ** DEPRECATED
  5189 **
  5190 ** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
  5191 ** interface.  This routine is provided for historical compatibility
  5192 ** only.  All new applications should use the
  5193 ** [sqlite3_soft_heap_limit64()] interface rather than this one.
  5194 */
  5195 SQLITE_API SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);
  5196 
  5197 
  5198 /*
  5199 ** CAPI3REF: Extract Metadata About A Column Of A Table
  5200 **
  5201 ** ^This routine returns metadata about a specific column of a specific
  5202 ** database table accessible using the [database connection] handle
  5203 ** passed as the first function argument.
  5204 **
  5205 ** ^The column is identified by the second, third and fourth parameters to
  5206 ** this function. ^The second parameter is either the name of the database
  5207 ** (i.e. "main", "temp", or an attached database) containing the specified
  5208 ** table or NULL. ^If it is NULL, then all attached databases are searched
  5209 ** for the table using the same algorithm used by the database engine to
  5210 ** resolve unqualified table references.
  5211 **
  5212 ** ^The third and fourth parameters to this function are the table and column
  5213 ** name of the desired column, respectively. Neither of these parameters
  5214 ** may be NULL.
  5215 **
  5216 ** ^Metadata is returned by writing to the memory locations passed as the 5th
  5217 ** and subsequent parameters to this function. ^Any of these arguments may be
  5218 ** NULL, in which case the corresponding element of metadata is omitted.
  5219 **
  5220 ** ^(<blockquote>
  5221 ** <table border="1">
  5222 ** <tr><th> Parameter <th> Output<br>Type <th>  Description
  5223 **
  5224 ** <tr><td> 5th <td> const char* <td> Data type
  5225 ** <tr><td> 6th <td> const char* <td> Name of default collation sequence
  5226 ** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
  5227 ** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
  5228 ** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
  5229 ** </table>
  5230 ** </blockquote>)^
  5231 **
  5232 ** ^The memory pointed to by the character pointers returned for the
  5233 ** declaration type and collation sequence is valid only until the next
  5234 ** call to any SQLite API function.
  5235 **
  5236 ** ^If the specified table is actually a view, an [error code] is returned.
  5237 **
  5238 ** ^If the specified column is "rowid", "oid" or "_rowid_" and an
  5239 ** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
  5240 ** parameters are set for the explicitly declared column. ^(If there is no
  5241 ** explicitly declared [INTEGER PRIMARY KEY] column, then the output
  5242 ** parameters are set as follows:
  5243 **
  5244 ** <pre>
  5245 **     data type: "INTEGER"
  5246 **     collation sequence: "BINARY"
  5247 **     not null: 0
  5248 **     primary key: 1
  5249 **     auto increment: 0
  5250 ** </pre>)^
  5251 **
  5252 ** ^(This function may load one or more schemas from database files. If an
  5253 ** error occurs during this process, or if the requested table or column
  5254 ** cannot be found, an [error code] is returned and an error message left
  5255 ** in the [database connection] (to be retrieved using sqlite3_errmsg()).)^
  5256 **
  5257 ** ^This API is only available if the library was compiled with the
  5258 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
  5259 */
  5260 SQLITE_API int sqlite3_table_column_metadata(
  5261   sqlite3 *db,                /* Connection handle */
  5262   const char *zDbName,        /* Database name or NULL */
  5263   const char *zTableName,     /* Table name */
  5264   const char *zColumnName,    /* Column name */
  5265   char const **pzDataType,    /* OUTPUT: Declared data type */
  5266   char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
  5267   int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
  5268   int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
  5269   int *pAutoinc               /* OUTPUT: True if column is auto-increment */
  5270 );
  5271 
  5272 /*
  5273 ** CAPI3REF: Load An Extension
  5274 **
  5275 ** ^This interface loads an SQLite extension library from the named file.
  5276 **
  5277 ** ^The sqlite3_load_extension() interface attempts to load an
  5278 ** [SQLite extension] library contained in the file zFile.  If
  5279 ** the file cannot be loaded directly, attempts are made to load
  5280 ** with various operating-system specific extensions added.
  5281 ** So for example, if "samplelib" cannot be loaded, then names like
  5282 ** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might
  5283 ** be tried also.
  5284 **
  5285 ** ^The entry point is zProc.
  5286 ** ^(zProc may be 0, in which case SQLite will try to come up with an
  5287 ** entry point name on its own.  It first tries "sqlite3_extension_init".
  5288 ** If that does not work, it constructs a name "sqlite3_X_init" where the
  5289 ** X is consists of the lower-case equivalent of all ASCII alphabetic
  5290 ** characters in the filename from the last "/" to the first following
  5291 ** "." and omitting any initial "lib".)^
  5292 ** ^The sqlite3_load_extension() interface returns
  5293 ** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
  5294 ** ^If an error occurs and pzErrMsg is not 0, then the
  5295 ** [sqlite3_load_extension()] interface shall attempt to
  5296 ** fill *pzErrMsg with error message text stored in memory
  5297 ** obtained from [sqlite3_malloc()]. The calling function
  5298 ** should free this memory by calling [sqlite3_free()].
  5299 **
  5300 ** ^Extension loading must be enabled using
  5301 ** [sqlite3_enable_load_extension()] prior to calling this API,
  5302 ** otherwise an error will be returned.
  5303 **
  5304 ** See also the [load_extension() SQL function].
  5305 */
  5306 SQLITE_API int sqlite3_load_extension(
  5307   sqlite3 *db,          /* Load the extension into this database connection */
  5308   const char *zFile,    /* Name of the shared library containing extension */
  5309   const char *zProc,    /* Entry point.  Derived from zFile if 0 */
  5310   char **pzErrMsg       /* Put error message here if not 0 */
  5311 );
  5312 
  5313 /*
  5314 ** CAPI3REF: Enable Or Disable Extension Loading
  5315 **
  5316 ** ^So as not to open security holes in older applications that are
  5317 ** unprepared to deal with [extension loading], and as a means of disabling
  5318 ** [extension loading] while evaluating user-entered SQL, the following API
  5319 ** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
  5320 **
  5321 ** ^Extension loading is off by default.
  5322 ** ^Call the sqlite3_enable_load_extension() routine with onoff==1
  5323 ** to turn extension loading on and call it with onoff==0 to turn
  5324 ** it back off again.
  5325 */
  5326 SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
  5327 
  5328 /*
  5329 ** CAPI3REF: Automatically Load Statically Linked Extensions
  5330 **
  5331 ** ^This interface causes the xEntryPoint() function to be invoked for
  5332 ** each new [database connection] that is created.  The idea here is that
  5333 ** xEntryPoint() is the entry point for a statically linked [SQLite extension]
  5334 ** that is to be automatically loaded into all new database connections.
  5335 **
  5336 ** ^(Even though the function prototype shows that xEntryPoint() takes
  5337 ** no arguments and returns void, SQLite invokes xEntryPoint() with three
  5338 ** arguments and expects and integer result as if the signature of the
  5339 ** entry point where as follows:
  5340 **
  5341 ** <blockquote><pre>
  5342 ** &nbsp;  int xEntryPoint(
  5343 ** &nbsp;    sqlite3 *db,
  5344 ** &nbsp;    const char **pzErrMsg,
  5345 ** &nbsp;    const struct sqlite3_api_routines *pThunk
  5346 ** &nbsp;  );
  5347 ** </pre></blockquote>)^
  5348 **
  5349 ** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
  5350 ** point to an appropriate error message (obtained from [sqlite3_mprintf()])
  5351 ** and return an appropriate [error code].  ^SQLite ensures that *pzErrMsg
  5352 ** is NULL before calling the xEntryPoint().  ^SQLite will invoke
  5353 ** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns.  ^If any
  5354 ** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
  5355 ** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
  5356 **
  5357 ** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
  5358 ** on the list of automatic extensions is a harmless no-op. ^No entry point
  5359 ** will be called more than once for each database connection that is opened.
  5360 **
  5361 ** See also: [sqlite3_reset_auto_extension()]
  5362 ** and [sqlite3_cancel_auto_extension()]
  5363 */
  5364 SQLITE_API int sqlite3_auto_extension(void (*xEntryPoint)(void));
  5365 
  5366 /*
  5367 ** CAPI3REF: Cancel Automatic Extension Loading
  5368 **
  5369 ** ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the
  5370 ** initialization routine X that was registered using a prior call to
  5371 ** [sqlite3_auto_extension(X)].  ^The [sqlite3_cancel_auto_extension(X)]
  5372 ** routine returns 1 if initialization routine X was successfully 
  5373 ** unregistered and it returns 0 if X was not on the list of initialization
  5374 ** routines.
  5375 */
  5376 SQLITE_API int sqlite3_cancel_auto_extension(void (*xEntryPoint)(void));
  5377 
  5378 /*
  5379 ** CAPI3REF: Reset Automatic Extension Loading
  5380 **
  5381 ** ^This interface disables all automatic extensions previously
  5382 ** registered using [sqlite3_auto_extension()].
  5383 */
  5384 SQLITE_API void sqlite3_reset_auto_extension(void);
  5385 
  5386 /*
  5387 ** The interface to the virtual-table mechanism is currently considered
  5388 ** to be experimental.  The interface might change in incompatible ways.
  5389 ** If this is a problem for you, do not use the interface at this time.
  5390 **
  5391 ** When the virtual-table mechanism stabilizes, we will declare the
  5392 ** interface fixed, support it indefinitely, and remove this comment.
  5393 */
  5394 
  5395 /*
  5396 ** Structures used by the virtual table interface
  5397 */
  5398 typedef struct sqlite3_vtab sqlite3_vtab;
  5399 typedef struct sqlite3_index_info sqlite3_index_info;
  5400 typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
  5401 typedef struct sqlite3_module sqlite3_module;
  5402 
  5403 /*
  5404 ** CAPI3REF: Virtual Table Object
  5405 ** KEYWORDS: sqlite3_module {virtual table module}
  5406 **
  5407 ** This structure, sometimes called a "virtual table module", 
  5408 ** defines the implementation of a [virtual tables].  
  5409 ** This structure consists mostly of methods for the module.
  5410 **
  5411 ** ^A virtual table module is created by filling in a persistent
  5412 ** instance of this structure and passing a pointer to that instance
  5413 ** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
  5414 ** ^The registration remains valid until it is replaced by a different
  5415 ** module or until the [database connection] closes.  The content
  5416 ** of this structure must not change while it is registered with
  5417 ** any database connection.
  5418 */
  5419 struct sqlite3_module {
  5420   int iVersion;
  5421   int (*xCreate)(sqlite3*, void *pAux,
  5422                int argc, const char *const*argv,
  5423                sqlite3_vtab **ppVTab, char**);
  5424   int (*xConnect)(sqlite3*, void *pAux,
  5425                int argc, const char *const*argv,
  5426                sqlite3_vtab **ppVTab, char**);
  5427   int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
  5428   int (*xDisconnect)(sqlite3_vtab *pVTab);
  5429   int (*xDestroy)(sqlite3_vtab *pVTab);
  5430   int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
  5431   int (*xClose)(sqlite3_vtab_cursor*);
  5432   int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
  5433                 int argc, sqlite3_value **argv);
  5434   int (*xNext)(sqlite3_vtab_cursor*);
  5435   int (*xEof)(sqlite3_vtab_cursor*);
  5436   int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
  5437   int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
  5438   int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
  5439   int (*xBegin)(sqlite3_vtab *pVTab);
  5440   int (*xSync)(sqlite3_vtab *pVTab);
  5441   int (*xCommit)(sqlite3_vtab *pVTab);
  5442   int (*xRollback)(sqlite3_vtab *pVTab);
  5443   int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
  5444                        void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
  5445                        void **ppArg);
  5446   int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
  5447   /* The methods above are in version 1 of the sqlite_module object. Those 
  5448   ** below are for version 2 and greater. */
  5449   int (*xSavepoint)(sqlite3_vtab *pVTab, int);
  5450   int (*xRelease)(sqlite3_vtab *pVTab, int);
  5451   int (*xRollbackTo)(sqlite3_vtab *pVTab, int);
  5452 };
  5453 
  5454 /*
  5455 ** CAPI3REF: Virtual Table Indexing Information
  5456 ** KEYWORDS: sqlite3_index_info
  5457 **
  5458 ** The sqlite3_index_info structure and its substructures is used as part
  5459 ** of the [virtual table] interface to
  5460 ** pass information into and receive the reply from the [xBestIndex]
  5461 ** method of a [virtual table module].  The fields under **Inputs** are the
  5462 ** inputs to xBestIndex and are read-only.  xBestIndex inserts its
  5463 ** results into the **Outputs** fields.
  5464 **
  5465 ** ^(The aConstraint[] array records WHERE clause constraints of the form:
  5466 **
  5467 ** <blockquote>column OP expr</blockquote>
  5468 **
  5469 ** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^  ^(The particular operator is
  5470 ** stored in aConstraint[].op using one of the
  5471 ** [SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_ values].)^
  5472 ** ^(The index of the column is stored in
  5473 ** aConstraint[].iColumn.)^  ^(aConstraint[].usable is TRUE if the
  5474 ** expr on the right-hand side can be evaluated (and thus the constraint
  5475 ** is usable) and false if it cannot.)^
  5476 **
  5477 ** ^The optimizer automatically inverts terms of the form "expr OP column"
  5478 ** and makes other simplifications to the WHERE clause in an attempt to
  5479 ** get as many WHERE clause terms into the form shown above as possible.
  5480 ** ^The aConstraint[] array only reports WHERE clause terms that are
  5481 ** relevant to the particular virtual table being queried.
  5482 **
  5483 ** ^Information about the ORDER BY clause is stored in aOrderBy[].
  5484 ** ^Each term of aOrderBy records a column of the ORDER BY clause.
  5485 **
  5486 ** The [xBestIndex] method must fill aConstraintUsage[] with information
  5487 ** about what parameters to pass to xFilter.  ^If argvIndex>0 then
  5488 ** the right-hand side of the corresponding aConstraint[] is evaluated
  5489 ** and becomes the argvIndex-th entry in argv.  ^(If aConstraintUsage[].omit
  5490 ** is true, then the constraint is assumed to be fully handled by the
  5491 ** virtual table and is not checked again by SQLite.)^
  5492 **
  5493 ** ^The idxNum and idxPtr values are recorded and passed into the
  5494 ** [xFilter] method.
  5495 ** ^[sqlite3_free()] is used to free idxPtr if and only if
  5496 ** needToFreeIdxPtr is true.
  5497 **
  5498 ** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
  5499 ** the correct order to satisfy the ORDER BY clause so that no separate
  5500 ** sorting step is required.
  5501 **
  5502 ** ^The estimatedCost value is an estimate of the cost of a particular
  5503 ** strategy. A cost of N indicates that the cost of the strategy is similar
  5504 ** to a linear scan of an SQLite table with N rows. A cost of log(N) 
  5505 ** indicates that the expense of the operation is similar to that of a
  5506 ** binary search on a unique indexed field of an SQLite table with N rows.
  5507 **
  5508 ** ^The estimatedRows value is an estimate of the number of rows that
  5509 ** will be returned by the strategy.
  5510 **
  5511 ** IMPORTANT: The estimatedRows field was added to the sqlite3_index_info
  5512 ** structure for SQLite version 3.8.2. If a virtual table extension is
  5513 ** used with an SQLite version earlier than 3.8.2, the results of attempting 
  5514 ** to read or write the estimatedRows field are undefined (but are likely 
  5515 ** to included crashing the application). The estimatedRows field should
  5516 ** therefore only be used if [sqlite3_libversion_number()] returns a
  5517 ** value greater than or equal to 3008002.
  5518 */
  5519 struct sqlite3_index_info {
  5520   /* Inputs */
  5521   int nConstraint;           /* Number of entries in aConstraint */
  5522   struct sqlite3_index_constraint {
  5523      int iColumn;              /* Column on left-hand side of constraint */
  5524      unsigned char op;         /* Constraint operator */
  5525      unsigned char usable;     /* True if this constraint is usable */
  5526      int iTermOffset;          /* Used internally - xBestIndex should ignore */
  5527   } *aConstraint;            /* Table of WHERE clause constraints */
  5528   int nOrderBy;              /* Number of terms in the ORDER BY clause */
  5529   struct sqlite3_index_orderby {
  5530      int iColumn;              /* Column number */
  5531      unsigned char desc;       /* True for DESC.  False for ASC. */
  5532   } *aOrderBy;               /* The ORDER BY clause */
  5533   /* Outputs */
  5534   struct sqlite3_index_constraint_usage {
  5535     int argvIndex;           /* if >0, constraint is part of argv to xFilter */
  5536     unsigned char omit;      /* Do not code a test for this constraint */
  5537   } *aConstraintUsage;
  5538   int idxNum;                /* Number used to identify the index */
  5539   char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
  5540   int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
  5541   int orderByConsumed;       /* True if output is already ordered */
  5542   double estimatedCost;           /* Estimated cost of using this index */
  5543   /* Fields below are only available in SQLite 3.8.2 and later */
  5544   sqlite3_int64 estimatedRows;    /* Estimated number of rows returned */
  5545 };
  5546 
  5547 /*
  5548 ** CAPI3REF: Virtual Table Constraint Operator Codes
  5549 **
  5550 ** These macros defined the allowed values for the
  5551 ** [sqlite3_index_info].aConstraint[].op field.  Each value represents
  5552 ** an operator that is part of a constraint term in the wHERE clause of
  5553 ** a query that uses a [virtual table].
  5554 */
  5555 #define SQLITE_INDEX_CONSTRAINT_EQ    2
  5556 #define SQLITE_INDEX_CONSTRAINT_GT    4
  5557 #define SQLITE_INDEX_CONSTRAINT_LE    8
  5558 #define SQLITE_INDEX_CONSTRAINT_LT    16
  5559 #define SQLITE_INDEX_CONSTRAINT_GE    32
  5560 #define SQLITE_INDEX_CONSTRAINT_MATCH 64
  5561 
  5562 /*
  5563 ** CAPI3REF: Register A Virtual Table Implementation
  5564 **
  5565 ** ^These routines are used to register a new [virtual table module] name.
  5566 ** ^Module names must be registered before
  5567 ** creating a new [virtual table] using the module and before using a
  5568 ** preexisting [virtual table] for the module.
  5569 **
  5570 ** ^The module name is registered on the [database connection] specified
  5571 ** by the first parameter.  ^The name of the module is given by the 
  5572 ** second parameter.  ^The third parameter is a pointer to
  5573 ** the implementation of the [virtual table module].   ^The fourth
  5574 ** parameter is an arbitrary client data pointer that is passed through
  5575 ** into the [xCreate] and [xConnect] methods of the virtual table module
  5576 ** when a new virtual table is be being created or reinitialized.
  5577 **
  5578 ** ^The sqlite3_create_module_v2() interface has a fifth parameter which
  5579 ** is a pointer to a destructor for the pClientData.  ^SQLite will
  5580 ** invoke the destructor function (if it is not NULL) when SQLite
  5581 ** no longer needs the pClientData pointer.  ^The destructor will also
  5582 ** be invoked if the call to sqlite3_create_module_v2() fails.
  5583 ** ^The sqlite3_create_module()
  5584 ** interface is equivalent to sqlite3_create_module_v2() with a NULL
  5585 ** destructor.
  5586 */
  5587 SQLITE_API int sqlite3_create_module(
  5588   sqlite3 *db,               /* SQLite connection to register module with */
  5589   const char *zName,         /* Name of the module */
  5590   const sqlite3_module *p,   /* Methods for the module */
  5591   void *pClientData          /* Client data for xCreate/xConnect */
  5592 );
  5593 SQLITE_API int sqlite3_create_module_v2(
  5594   sqlite3 *db,               /* SQLite connection to register module with */
  5595   const char *zName,         /* Name of the module */
  5596   const sqlite3_module *p,   /* Methods for the module */
  5597   void *pClientData,         /* Client data for xCreate/xConnect */
  5598   void(*xDestroy)(void*)     /* Module destructor function */
  5599 );
  5600 
  5601 /*
  5602 ** CAPI3REF: Virtual Table Instance Object
  5603 ** KEYWORDS: sqlite3_vtab
  5604 **
  5605 ** Every [virtual table module] implementation uses a subclass
  5606 ** of this object to describe a particular instance
  5607 ** of the [virtual table].  Each subclass will
  5608 ** be tailored to the specific needs of the module implementation.
  5609 ** The purpose of this superclass is to define certain fields that are
  5610 ** common to all module implementations.
  5611 **
  5612 ** ^Virtual tables methods can set an error message by assigning a
  5613 ** string obtained from [sqlite3_mprintf()] to zErrMsg.  The method should
  5614 ** take care that any prior string is freed by a call to [sqlite3_free()]
  5615 ** prior to assigning a new string to zErrMsg.  ^After the error message
  5616 ** is delivered up to the client application, the string will be automatically
  5617 ** freed by sqlite3_free() and the zErrMsg field will be zeroed.
  5618 */
  5619 struct sqlite3_vtab {
  5620   const sqlite3_module *pModule;  /* The module for this virtual table */
  5621   int nRef;                       /* NO LONGER USED */
  5622   char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
  5623   /* Virtual table implementations will typically add additional fields */
  5624 };
  5625 
  5626 /*
  5627 ** CAPI3REF: Virtual Table Cursor Object
  5628 ** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}
  5629 **
  5630 ** Every [virtual table module] implementation uses a subclass of the
  5631 ** following structure to describe cursors that point into the
  5632 ** [virtual table] and are used
  5633 ** to loop through the virtual table.  Cursors are created using the
  5634 ** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
  5635 ** by the [sqlite3_module.xClose | xClose] method.  Cursors are used
  5636 ** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods
  5637 ** of the module.  Each module implementation will define
  5638 ** the content of a cursor structure to suit its own needs.
  5639 **
  5640 ** This superclass exists in order to define fields of the cursor that
  5641 ** are common to all implementations.
  5642 */
  5643 struct sqlite3_vtab_cursor {
  5644   sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
  5645   /* Virtual table implementations will typically add additional fields */
  5646 };
  5647 
  5648 /*
  5649 ** CAPI3REF: Declare The Schema Of A Virtual Table
  5650 **
  5651 ** ^The [xCreate] and [xConnect] methods of a
  5652 ** [virtual table module] call this interface
  5653 ** to declare the format (the names and datatypes of the columns) of
  5654 ** the virtual tables they implement.
  5655 */
  5656 SQLITE_API int sqlite3_declare_vtab(sqlite3*, const char *zSQL);
  5657 
  5658 /*
  5659 ** CAPI3REF: Overload A Function For A Virtual Table
  5660 **
  5661 ** ^(Virtual tables can provide alternative implementations of functions
  5662 ** using the [xFindFunction] method of the [virtual table module].  
  5663 ** But global versions of those functions
  5664 ** must exist in order to be overloaded.)^
  5665 **
  5666 ** ^(This API makes sure a global version of a function with a particular
  5667 ** name and number of parameters exists.  If no such function exists
  5668 ** before this API is called, a new function is created.)^  ^The implementation
  5669 ** of the new function always causes an exception to be thrown.  So
  5670 ** the new function is not good for anything by itself.  Its only
  5671 ** purpose is to be a placeholder function that can be overloaded
  5672 ** by a [virtual table].
  5673 */
  5674 SQLITE_API int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);
  5675 
  5676 /*
  5677 ** The interface to the virtual-table mechanism defined above (back up
  5678 ** to a comment remarkably similar to this one) is currently considered
  5679 ** to be experimental.  The interface might change in incompatible ways.
  5680 ** If this is a problem for you, do not use the interface at this time.
  5681 **
  5682 ** When the virtual-table mechanism stabilizes, we will declare the
  5683 ** interface fixed, support it indefinitely, and remove this comment.
  5684 */
  5685 
  5686 /*
  5687 ** CAPI3REF: A Handle To An Open BLOB
  5688 ** KEYWORDS: {BLOB handle} {BLOB handles}
  5689 **
  5690 ** An instance of this object represents an open BLOB on which
  5691 ** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
  5692 ** ^Objects of this type are created by [sqlite3_blob_open()]
  5693 ** and destroyed by [sqlite3_blob_close()].
  5694 ** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
  5695 ** can be used to read or write small subsections of the BLOB.
  5696 ** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
  5697 */
  5698 typedef struct sqlite3_blob sqlite3_blob;
  5699 
  5700 /*
  5701 ** CAPI3REF: Open A BLOB For Incremental I/O
  5702 **
  5703 ** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located
  5704 ** in row iRow, column zColumn, table zTable in database zDb;
  5705 ** in other words, the same BLOB that would be selected by:
  5706 **
  5707 ** <pre>
  5708 **     SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
  5709 ** </pre>)^
  5710 **
  5711 ** ^If the flags parameter is non-zero, then the BLOB is opened for read
  5712 ** and write access. ^If it is zero, the BLOB is opened for read access.
  5713 ** ^It is not possible to open a column that is part of an index or primary 
  5714 ** key for writing. ^If [foreign key constraints] are enabled, it is 
  5715 ** not possible to open a column that is part of a [child key] for writing.
  5716 **
  5717 ** ^Note that the database name is not the filename that contains
  5718 ** the database but rather the symbolic name of the database that
  5719 ** appears after the AS keyword when the database is connected using [ATTACH].
  5720 ** ^For the main database file, the database name is "main".
  5721 ** ^For TEMP tables, the database name is "temp".
  5722 **
  5723 ** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
  5724 ** to *ppBlob. Otherwise an [error code] is returned and *ppBlob is set
  5725 ** to be a null pointer.)^
  5726 ** ^This function sets the [database connection] error code and message
  5727 ** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related
  5728 ** functions. ^Note that the *ppBlob variable is always initialized in a
  5729 ** way that makes it safe to invoke [sqlite3_blob_close()] on *ppBlob
  5730 ** regardless of the success or failure of this routine.
  5731 **
  5732 ** ^(If the row that a BLOB handle points to is modified by an
  5733 ** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
  5734 ** then the BLOB handle is marked as "expired".
  5735 ** This is true if any column of the row is changed, even a column
  5736 ** other than the one the BLOB handle is open on.)^
  5737 ** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
  5738 ** an expired BLOB handle fail with a return code of [SQLITE_ABORT].
  5739 ** ^(Changes written into a BLOB prior to the BLOB expiring are not
  5740 ** rolled back by the expiration of the BLOB.  Such changes will eventually
  5741 ** commit if the transaction continues to completion.)^
  5742 **
  5743 ** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
  5744 ** the opened blob.  ^The size of a blob may not be changed by this
  5745 ** interface.  Use the [UPDATE] SQL command to change the size of a
  5746 ** blob.
  5747 **
  5748 ** ^The [sqlite3_blob_open()] interface will fail for a [WITHOUT ROWID]
  5749 ** table.  Incremental BLOB I/O is not possible on [WITHOUT ROWID] tables.
  5750 **
  5751 ** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
  5752 ** and the built-in [zeroblob] SQL function can be used, if desired,
  5753 ** to create an empty, zero-filled blob in which to read or write using
  5754 ** this interface.
  5755 **
  5756 ** To avoid a resource leak, every open [BLOB handle] should eventually
  5757 ** be released by a call to [sqlite3_blob_close()].
  5758 */
  5759 SQLITE_API int sqlite3_blob_open(
  5760   sqlite3*,
  5761   const char *zDb,
  5762   const char *zTable,
  5763   const char *zColumn,
  5764   sqlite3_int64 iRow,
  5765   int flags,
  5766   sqlite3_blob **ppBlob
  5767 );
  5768 
  5769 /*
  5770 ** CAPI3REF: Move a BLOB Handle to a New Row
  5771 **
  5772 ** ^This function is used to move an existing blob handle so that it points
  5773 ** to a different row of the same database table. ^The new row is identified
  5774 ** by the rowid value passed as the second argument. Only the row can be
  5775 ** changed. ^The database, table and column on which the blob handle is open
  5776 ** remain the same. Moving an existing blob handle to a new row can be
  5777 ** faster than closing the existing handle and opening a new one.
  5778 **
  5779 ** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -
  5780 ** it must exist and there must be either a blob or text value stored in
  5781 ** the nominated column.)^ ^If the new row is not present in the table, or if
  5782 ** it does not contain a blob or text value, or if another error occurs, an
  5783 ** SQLite error code is returned and the blob handle is considered aborted.
  5784 ** ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or
  5785 ** [sqlite3_blob_reopen()] on an aborted blob handle immediately return
  5786 ** SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle
  5787 ** always returns zero.
  5788 **
  5789 ** ^This function sets the database handle error code and message.
  5790 */
  5791 SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_blob_reopen(sqlite3_blob *, sqlite3_int64);
  5792 
  5793 /*
  5794 ** CAPI3REF: Close A BLOB Handle
  5795 **
  5796 ** ^Closes an open [BLOB handle].
  5797 **
  5798 ** ^Closing a BLOB shall cause the current transaction to commit
  5799 ** if there are no other BLOBs, no pending prepared statements, and the
  5800 ** database connection is in [autocommit mode].
  5801 ** ^If any writes were made to the BLOB, they might be held in cache
  5802 ** until the close operation if they will fit.
  5803 **
  5804 ** ^(Closing the BLOB often forces the changes
  5805 ** out to disk and so if any I/O errors occur, they will likely occur
  5806 ** at the time when the BLOB is closed.  Any errors that occur during
  5807 ** closing are reported as a non-zero return value.)^
  5808 **
  5809 ** ^(The BLOB is closed unconditionally.  Even if this routine returns
  5810 ** an error code, the BLOB is still closed.)^
  5811 **
  5812 ** ^Calling this routine with a null pointer (such as would be returned
  5813 ** by a failed call to [sqlite3_blob_open()]) is a harmless no-op.
  5814 */
  5815 SQLITE_API int sqlite3_blob_close(sqlite3_blob *);
  5816 
  5817 /*
  5818 ** CAPI3REF: Return The Size Of An Open BLOB
  5819 **
  5820 ** ^Returns the size in bytes of the BLOB accessible via the 
  5821 ** successfully opened [BLOB handle] in its only argument.  ^The
  5822 ** incremental blob I/O routines can only read or overwriting existing
  5823 ** blob content; they cannot change the size of a blob.
  5824 **
  5825 ** This routine only works on a [BLOB handle] which has been created
  5826 ** by a prior successful call to [sqlite3_blob_open()] and which has not
  5827 ** been closed by [sqlite3_blob_close()].  Passing any other pointer in
  5828 ** to this routine results in undefined and probably undesirable behavior.
  5829 */
  5830 SQLITE_API int sqlite3_blob_bytes(sqlite3_blob *);
  5831 
  5832 /*
  5833 ** CAPI3REF: Read Data From A BLOB Incrementally
  5834 **
  5835 ** ^(This function is used to read data from an open [BLOB handle] into a
  5836 ** caller-supplied buffer. N bytes of data are copied into buffer Z
  5837 ** from the open BLOB, starting at offset iOffset.)^
  5838 **
  5839 ** ^If offset iOffset is less than N bytes from the end of the BLOB,
  5840 ** [SQLITE_ERROR] is returned and no data is read.  ^If N or iOffset is
  5841 ** less than zero, [SQLITE_ERROR] is returned and no data is read.
  5842 ** ^The size of the blob (and hence the maximum value of N+iOffset)
  5843 ** can be determined using the [sqlite3_blob_bytes()] interface.
  5844 **
  5845 ** ^An attempt to read from an expired [BLOB handle] fails with an
  5846 ** error code of [SQLITE_ABORT].
  5847 **
  5848 ** ^(On success, sqlite3_blob_read() returns SQLITE_OK.
  5849 ** Otherwise, an [error code] or an [extended error code] is returned.)^
  5850 **
  5851 ** This routine only works on a [BLOB handle] which has been created
  5852 ** by a prior successful call to [sqlite3_blob_open()] and which has not
  5853 ** been closed by [sqlite3_blob_close()].  Passing any other pointer in
  5854 ** to this routine results in undefined and probably undesirable behavior.
  5855 **
  5856 ** See also: [sqlite3_blob_write()].
  5857 */
  5858 SQLITE_API int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);
  5859 
  5860 /*
  5861 ** CAPI3REF: Write Data Into A BLOB Incrementally
  5862 **
  5863 ** ^This function is used to write data into an open [BLOB handle] from a
  5864 ** caller-supplied buffer. ^N bytes of data are copied from the buffer Z
  5865 ** into the open BLOB, starting at offset iOffset.
  5866 **
  5867 ** ^If the [BLOB handle] passed as the first argument was not opened for
  5868 ** writing (the flags parameter to [sqlite3_blob_open()] was zero),
  5869 ** this function returns [SQLITE_READONLY].
  5870 **
  5871 ** ^This function may only modify the contents of the BLOB; it is
  5872 ** not possible to increase the size of a BLOB using this API.
  5873 ** ^If offset iOffset is less than N bytes from the end of the BLOB,
  5874 ** [SQLITE_ERROR] is returned and no data is written.  ^If N is
  5875 ** less than zero [SQLITE_ERROR] is returned and no data is written.
  5876 ** The size of the BLOB (and hence the maximum value of N+iOffset)
  5877 ** can be determined using the [sqlite3_blob_bytes()] interface.
  5878 **
  5879 ** ^An attempt to write to an expired [BLOB handle] fails with an
  5880 ** error code of [SQLITE_ABORT].  ^Writes to the BLOB that occurred
  5881 ** before the [BLOB handle] expired are not rolled back by the
  5882 ** expiration of the handle, though of course those changes might
  5883 ** have been overwritten by the statement that expired the BLOB handle
  5884 ** or by other independent statements.
  5885 **
  5886 ** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
  5887 ** Otherwise, an  [error code] or an [extended error code] is returned.)^
  5888 **
  5889 ** This routine only works on a [BLOB handle] which has been created
  5890 ** by a prior successful call to [sqlite3_blob_open()] and which has not
  5891 ** been closed by [sqlite3_blob_close()].  Passing any other pointer in
  5892 ** to this routine results in undefined and probably undesirable behavior.
  5893 **
  5894 ** See also: [sqlite3_blob_read()].
  5895 */
  5896 SQLITE_API int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);
  5897 
  5898 /*
  5899 ** CAPI3REF: Virtual File System Objects
  5900 **
  5901 ** A virtual filesystem (VFS) is an [sqlite3_vfs] object
  5902 ** that SQLite uses to interact
  5903 ** with the underlying operating system.  Most SQLite builds come with a
  5904 ** single default VFS that is appropriate for the host computer.
  5905 ** New VFSes can be registered and existing VFSes can be unregistered.
  5906 ** The following interfaces are provided.
  5907 **
  5908 ** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
  5909 ** ^Names are case sensitive.
  5910 ** ^Names are zero-terminated UTF-8 strings.
  5911 ** ^If there is no match, a NULL pointer is returned.
  5912 ** ^If zVfsName is NULL then the default VFS is returned.
  5913 **
  5914 ** ^New VFSes are registered with sqlite3_vfs_register().
  5915 ** ^Each new VFS becomes the default VFS if the makeDflt flag is set.
  5916 ** ^The same VFS can be registered multiple times without injury.
  5917 ** ^To make an existing VFS into the default VFS, register it again
  5918 ** with the makeDflt flag set.  If two different VFSes with the
  5919 ** same name are registered, the behavior is undefined.  If a
  5920 ** VFS is registered with a name that is NULL or an empty string,
  5921 ** then the behavior is undefined.
  5922 **
  5923 ** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.
  5924 ** ^(If the default VFS is unregistered, another VFS is chosen as
  5925 ** the default.  The choice for the new VFS is arbitrary.)^
  5926 */
  5927 SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
  5928 SQLITE_API int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
  5929 SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs*);
  5930 
  5931 /*
  5932 ** CAPI3REF: Mutexes
  5933 **
  5934 ** The SQLite core uses these routines for thread
  5935 ** synchronization. Though they are intended for internal
  5936 ** use by SQLite, code that links against SQLite is
  5937 ** permitted to use any of these routines.
  5938 **
  5939 ** The SQLite source code contains multiple implementations
  5940 ** of these mutex routines.  An appropriate implementation
  5941 ** is selected automatically at compile-time.  ^(The following
  5942 ** implementations are available in the SQLite core:
  5943 **
  5944 ** <ul>
  5945 ** <li>   SQLITE_MUTEX_PTHREADS
  5946 ** <li>   SQLITE_MUTEX_W32
  5947 ** <li>   SQLITE_MUTEX_NOOP
  5948 ** </ul>)^
  5949 **
  5950 ** ^The SQLITE_MUTEX_NOOP implementation is a set of routines
  5951 ** that does no real locking and is appropriate for use in
  5952 ** a single-threaded application.  ^The SQLITE_MUTEX_PTHREADS and
  5953 ** SQLITE_MUTEX_W32 implementations are appropriate for use on Unix
  5954 ** and Windows.
  5955 **
  5956 ** ^(If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
  5957 ** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
  5958 ** implementation is included with the library. In this case the
  5959 ** application must supply a custom mutex implementation using the
  5960 ** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
  5961 ** before calling sqlite3_initialize() or any other public sqlite3_
  5962 ** function that calls sqlite3_initialize().)^
  5963 **
  5964 ** ^The sqlite3_mutex_alloc() routine allocates a new
  5965 ** mutex and returns a pointer to it. ^If it returns NULL
  5966 ** that means that a mutex could not be allocated.  ^SQLite
  5967 ** will unwind its stack and return an error.  ^(The argument
  5968 ** to sqlite3_mutex_alloc() is one of these integer constants:
  5969 **
  5970 ** <ul>
  5971 ** <li>  SQLITE_MUTEX_FAST
  5972 ** <li>  SQLITE_MUTEX_RECURSIVE
  5973 ** <li>  SQLITE_MUTEX_STATIC_MASTER
  5974 ** <li>  SQLITE_MUTEX_STATIC_MEM
  5975 ** <li>  SQLITE_MUTEX_STATIC_OPEN
  5976 ** <li>  SQLITE_MUTEX_STATIC_PRNG
  5977 ** <li>  SQLITE_MUTEX_STATIC_LRU
  5978 ** <li>  SQLITE_MUTEX_STATIC_PMEM
  5979 ** <li>  SQLITE_MUTEX_STATIC_APP1
  5980 ** <li>  SQLITE_MUTEX_STATIC_APP2
  5981 ** </ul>)^
  5982 **
  5983 ** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
  5984 ** cause sqlite3_mutex_alloc() to create
  5985 ** a new mutex.  ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
  5986 ** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
  5987 ** The mutex implementation does not need to make a distinction
  5988 ** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
  5989 ** not want to.  ^SQLite will only request a recursive mutex in
  5990 ** cases where it really needs one.  ^If a faster non-recursive mutex
  5991 ** implementation is available on the host platform, the mutex subsystem
  5992 ** might return such a mutex in response to SQLITE_MUTEX_FAST.
  5993 **
  5994 ** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other
  5995 ** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return
  5996 ** a pointer to a static preexisting mutex.  ^Six static mutexes are
  5997 ** used by the current version of SQLite.  Future versions of SQLite
  5998 ** may add additional static mutexes.  Static mutexes are for internal
  5999 ** use by SQLite only.  Applications that use SQLite mutexes should
  6000 ** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
  6001 ** SQLITE_MUTEX_RECURSIVE.
  6002 **
  6003 ** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
  6004 ** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
  6005 ** returns a different mutex on every call.  ^But for the static
  6006 ** mutex types, the same mutex is returned on every call that has
  6007 ** the same type number.
  6008 **
  6009 ** ^The sqlite3_mutex_free() routine deallocates a previously
  6010 ** allocated dynamic mutex.  ^SQLite is careful to deallocate every
  6011 ** dynamic mutex that it allocates.  The dynamic mutexes must not be in
  6012 ** use when they are deallocated.  Attempting to deallocate a static
  6013 ** mutex results in undefined behavior.  ^SQLite never deallocates
</