sqlite3.h

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***
** {F12261} This function returns the number of database rows that have been
** modified by INSERT, UPDATE or DELETE statements since the database handle
** was opened. {F12262} The count includes UPDATE, INSERT and DELETE 
** statements executed as part of trigger programs.  {F12263} All changes
** are counted as soon as the statement that makes them is completed 
** (when the statement handle is passed to [sqlite3_reset()] or 
** [sqlite3_finalize()]). {END}
**
** See also the [sqlite3_change()] interface.
**
** {F12265} SQLite implements the command "DELETE FROM table" without
** a WHERE clause by dropping and recreating the table.  (This is much
** faster than going
** through and deleting individual elements form the table.)  Because of
** this optimization, the change count for "DELETE FROM table" will be
** zero regardless of the number of elements that were originally in the
** table. To get an accurate count of the number of rows deleted, use
** "DELETE FROM table WHERE 1" instead.
**
** {U12264} If another thread makes changes on the same database connection
** while this routine is running then the return value of this routine
** is undefined. {END}
*/
int sqlite3_total_changes(sqlite3*);

/*
** CAPI3REF: Interrupt A Long-Running Query {F12270}
**
** {F12271} This function causes any pending database operation to abort and
** return at its earliest opportunity. {END} This routine is typically
** called in response to a user action such as pressing "Cancel"
** or Ctrl-C where the user wants a long query operation to halt
** immediately.
**
** {F12272} It is safe to call this routine from a thread different from the
** thread that is currently running the database operation. {U12273} But it
** is not safe to call this routine with a database connection that
** is closed or might close before sqlite3_interrupt() returns.
**
** If an SQL is very nearly finished at the time when sqlite3_interrupt()
** is called, then it might not have an opportunity to be interrupted.
** It might continue to completion.
** {F12274} The SQL operation that is interrupted will return
** [SQLITE_INTERRUPT].  {F12275} If the interrupted SQL operation is an
** INSERT, UPDATE, or DELETE that is inside an explicit transaction, 
** then the entire transaction will be rolled back automatically.
** {F12276} A call to sqlite3_interrupt() has no effect on SQL statements
** that are started after sqlite3_interrupt() returns.
*/
void sqlite3_interrupt(sqlite3*);

/*
** CAPI3REF: Determine If An SQL Statement Is Complete {F10510}
**
** These routines are useful for command-line input to determine if the
** currently entered text seems to form complete a SQL statement or
** if additional input is needed before sending the text into
** SQLite for parsing.  These routines return true if the input string
** appears to be a complete SQL statement.  A statement is judged to be
** complete if it ends with a semicolon and is not a fragment of a
** CREATE TRIGGER statement.  These routines do not parse the SQL and
** so will not detect syntactically incorrect SQL.
**
** {F10511} These functions return true if the given input string 
** ends with a semicolon optionally followed by whitespace or
** comments. {F10512} For sqlite3_complete(),
** the parameter must be a zero-terminated UTF-8 string. {F10513} For
** sqlite3_complete16(), a zero-terminated machine byte order UTF-16 string
** is required.  {F10514} These routines return false if the terminal
** semicolon is within a comment, a string literal or a quoted identifier
** (in other words if the final semicolon is not really a separate token
** but part of a larger token) or if the final semicolon is
** in between the BEGIN and END keywords of a CREATE TRIGGER statement.
** {END}
*/
int sqlite3_complete(const char *sql);
int sqlite3_complete16(const void *sql);

/*
** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors {F12310}
**
** {F12311} This routine identifies a callback function that might be
** invoked whenever an attempt is made to open a database table 
** that another thread or process has locked.
** {F12312} If the busy callback is NULL, then [SQLITE_BUSY]
** or [SQLITE_IOERR_BLOCKED]
** is returned immediately upon encountering the lock.
** {F12313} If the busy callback is not NULL, then the
** callback will be invoked with two arguments.  {F12314} The
** first argument to the handler is a copy of the void* pointer which
** is the third argument to this routine.  {F12315} The second argument to
** the handler is the number of times that the busy handler has
** been invoked for this locking event.  {F12316} If the
** busy callback returns 0, then no additional attempts are made to
** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned.
** {F12317} If the callback returns non-zero, then another attempt
** is made to open the database for reading and the cycle repeats.
**
** The presence of a busy handler does not guarantee that
** it will be invoked when there is lock contention. {F12319}
** If SQLite determines that invoking the busy handler could result in
** a deadlock, it will go ahead and return [SQLITE_BUSY] or
** [SQLITE_IOERR_BLOCKED] instead of invoking the
** busy handler. {END}
** Consider a scenario where one process is holding a read lock that
** it is trying to promote to a reserved lock and
** a second process is holding a reserved lock that it is trying
** to promote to an exclusive lock.  The first process cannot proceed
** because it is blocked by the second and the second process cannot
** proceed because it is blocked by the first.  If both processes
** invoke the busy handlers, neither will make any progress.  Therefore,
** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
** will induce the first process to release its read lock and allow
** the second process to proceed.
**
** {F12321} The default busy callback is NULL. {END}
**
** {F12322} The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED]
** when SQLite is in the middle of a large transaction where all the
** changes will not fit into the in-memory cache.  {F12323} SQLite will
** already hold a RESERVED lock on the database file, but it needs
** to promote this lock to EXCLUSIVE so that it can spill cache
** pages into the database file without harm to concurrent
** readers.  {F12324} If it is unable to promote the lock, then the in-memory
** cache will be left in an inconsistent state and so the error
** code is promoted from the relatively benign [SQLITE_BUSY] to
** the more severe [SQLITE_IOERR_BLOCKED].  {F12325} This error code promotion
** forces an automatic rollback of the changes. {END} See the
** <a href="http://www.sqlite.org/cvstrac/wiki?p=CorruptionFollowingBusyError">
** CorruptionFollowingBusyError</a> wiki page for a discussion of why
** this is important.
**	
** {F12326} Sqlite is re-entrant, so the busy handler may start a new
** query. {END} (It is not clear why anyone would every want to do this,
** but it is allowed, in theory.) {U12327} But the busy handler may not
** close the database.  Closing the database from a busy handler will delete 
** data structures out from under the executing query and will 
** probably result in a segmentation fault or other runtime error. {END}
**
** {F12328} There can only be a single busy handler defined for each database
** connection.  Setting a new busy handler clears any previous one. 
** {F12329} Note that calling [sqlite3_busy_timeout()] will also set or clear
** the busy handler.
**
** {F12331} When operating in [sqlite3_enable_shared_cache | shared cache mode],
** only a single busy handler can be defined for each database file.
** So if two database connections share a single cache, then changing
** the busy handler on one connection will also change the busy
** handler in the other connection.  {F12332} The busy handler is invoked
** in the thread that was running when the lock contention occurs.
*/
int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);

/*
** CAPI3REF: Set A Busy Timeout {F12340}
**
** {F12341} This routine sets a [sqlite3_busy_handler | busy handler]
** that sleeps for a while when a
** table is locked.  {F12342} The handler will sleep multiple times until 
** at least "ms" milliseconds of sleeping have been done. {F12343} After
** "ms" milliseconds of sleeping, the handler returns 0 which
** causes [sqlite3_step()] to return [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED].
**
** {F12344} Calling this routine with an argument less than or equal to zero
** turns off all busy handlers.
**
** {F12345} There can only be a single busy handler for a particular database
** connection.  If another busy handler was defined  
** (using [sqlite3_busy_handler()]) prior to calling
** this routine, that other busy handler is cleared.
*/
int sqlite3_busy_timeout(sqlite3*, int ms);

/*
** CAPI3REF: Convenience Routines For Running Queries {F12370}
**
** This next routine is a convenience wrapper around [sqlite3_exec()].
** {F12371} Instead of invoking a user-supplied callback for each row of the
** result, this routine remembers each row of the result in memory
** obtained from [sqlite3_malloc()], then returns all of the result after the
** query has finished. {F12372}
**
** As an example, suppose the query result where this table:
**
** <blockquote><pre>
**        Name        | Age
**        -----------------------
**        Alice       | 43
**        Bob         | 28
**        Cindy       | 21
** </pre></blockquote>
**
** If the 3rd argument were &azResult then after the function returns
** azResult will contain the following data:
**
** <blockquote><pre>
**        azResult&#91;0] = "Name";
**        azResult&#91;1] = "Age";
**        azResult&#91;2] = "Alice";
**        azResult&#91;3] = "43";
**        azResult&#91;4] = "Bob";
**        azResult&#91;5] = "28";
**        azResult&#91;6] = "Cindy";
**        azResult&#91;7] = "21";
** </pre></blockquote>
**
** Notice that there is an extra row of data containing the column
** headers.  But the *nrow return value is still 3.  *ncolumn is
** set to 2.  In general, the number of values inserted into azResult
** will be ((*nrow) + 1)*(*ncolumn).
**
** {U12374} After the calling function has finished using the result, it should 
** pass the result data pointer to sqlite3_free_table() in order to 
** release the memory that was malloc-ed.  Because of the way the 
** [sqlite3_malloc()] happens, the calling function must not try to call 
** [sqlite3_free()] directly.  Only [sqlite3_free_table()] is able to release 
** the memory properly and safely. {END}
**
** {F12373} The return value of this routine is the same as
** from [sqlite3_exec()].
*/
int sqlite3_get_table(
  sqlite3*,              /* An open database */
  const char *sql,       /* SQL to be executed */
  char ***resultp,       /* Result written to a char *[]  that this points to */
  int *nrow,             /* Number of result rows written here */
  int *ncolumn,          /* Number of result columns written here */
  char **errmsg          /* Error msg written here */
);
void sqlite3_free_table(char **result);

/*
** CAPI3REF: Formatted String Printing Functions {F17400}
**
** These routines are workalikes of the "printf()" family of functions
** from the standard C library.
**
** {F17401} The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
** results into memory obtained from [sqlite3_malloc()].
** {U17402} The strings returned by these two routines should be
** released by [sqlite3_free()]. {F17403}  Both routines return a
** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
** memory to hold the resulting string.
**
** {F17404} In sqlite3_snprintf() routine is similar to "snprintf()" from
** the standard C library.  The result is written into the
** buffer supplied as the second parameter whose size is given by
** the first parameter. {END} Note that the order of the
** first two parameters is reversed from snprintf().  This is an
** historical accident that cannot be fixed without breaking
** backwards compatibility.  {F17405} Note also that sqlite3_snprintf()
** returns a pointer to its buffer instead of the number of
** characters actually written into the buffer. {END} We admit that
** the number of characters written would be a more useful return
** value but we cannot change the implementation of sqlite3_snprintf()
** now without breaking compatibility.
**
** {F17406} As long as the buffer size is greater than zero, sqlite3_snprintf()
** guarantees that the buffer is always zero-terminated. {F17407} The first
** parameter "n" is the total size of the buffer, including space for
** the zero terminator.  {END} So the longest string that can be completely
** written will be n-1 characters.
**
** These routines all implement some additional formatting
** options that are useful for constructing SQL statements.
** All of the usual printf formatting options apply.  In addition, there
** is are "%q", "%Q", and "%z" options.
**
** {F17410} The %q option works like %s in that it substitutes a null-terminated
** string from the argument list.  But %q also doubles every '\'' character.
** %q is designed for use inside a string literal. {END} By doubling each '\''
** character it escapes that character and allows it to be inserted into
** the string.
**
** For example, so some string variable contains text as follows:
**
** <blockquote><pre>
**  char *zText = "It's a happy day!";
** </pre></blockquote>
**