src/sqlite.h.in

/*
** Copyright (c) 1999, 2000 D. Richard Hipp
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the GNU General Public
** License as published by the Free Software Foundation; either
** version 2 of the License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
** General Public License for more details.
** 
** You should have received a copy of the GNU General Public
** License along with this library; if not, write to the
** Free Software Foundation, Inc., 59 Temple Place - Suite 330,
** Boston, MA  02111-1307, USA.
**
** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*************************************************************************
** This header file defines the interface that the sqlite library
** presents to client programs.
**
** @(#) $Id: sqlite.h.in,v 1.7 2000/11/28 20:47:20 drh Exp $
*/
#ifndef _SQLITE_H_
#define _SQLITE_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** The version of the SQLite library.
*/
#define SQLITE_VERSION         "--VERS--"

/*
** The version string is also compiled into the library so that a program
** can check to make sure that the lib*.a file and the *.h file are from
** the same version.
*/
extern const char sqlite_version[];

/*
** Each open sqlite database is represented by an instance of the
** following opaque structure.
*/
typedef struct sqlite sqlite;

/*
** A function to open a new sqlite database.  
**
** If the database does not exist and mode indicates write
** permission, then a new database is created.  If the database
** does not exist and mode does not indicate write permission,
** then the open fails, an error message generated (if errmsg!=0)
** and the function returns 0.
** 
** If mode does not indicates user write permission, then the 
** database is opened read-only.
**
** The Truth:  As currently implemented, all databases are opened
** for writing all the time.  Maybe someday we will provide the
** ability to open a database readonly.  The mode parameters is
** provide in anticipation of that enhancement.
*/
sqlite *sqlite_open(const char *filename, int mode, char **errmsg);

/*
** A function to close the database.
**
** Call this function with a pointer to a structure that was previously
** returned from sqlite_open() and the corresponding database will by closed.
*/
void sqlite_close(sqlite *);

/*
** The type for a callback function.
*/
typedef int (*sqlite_callback)(void*,int,char**, char**);

/*
** A function to executes one or more statements of SQL.
**
** If one or more of the SQL statements are queries, then
** the callback function specified by the 3rd parameter is
** invoked once for each row of the query result.  This callback
** should normally return 0.  If the callback returns a non-zero
** value then the query is aborted, all subsequent SQL statements
** are skipped and the sqlite_exec() function returns the SQLITE_ABORT.
**
** The 4th parameter is an arbitrary pointer that is passed
** to the callback function as its first parameter.
**
** The 2nd parameter to the callback function is the number of
** columns in the query result.  The 3rd parameter is an array
** of string holding the values for each column.  The 4th parameter
** is an array of strings holding the names of each column.
**
** The callback function may be NULL, even for queries.  A NULL
** callback is not an error.  It just means that no callback
** will be invoked.
**
** If an error occurs while parsing or evaluating the SQL (but
** not while executing the callback) then an appropriate error
** message is written into memory obtained from malloc() and
** *errmsg is made to point to that message.  If errmsg==NULL,
** then no error message is ever written.  The return value is
** SQLITE_ERROR if an error occurs.  The calling function is
** responsible for freeing the memory that holds the error
** message.
**
** If the query could not be executed because a database file is
** locked or busy, then this function returns SQLITE_BUSY.  (This
** behavior can be modified somewhat using the sqlite_busy_handler()
** and sqlite_busy_timeout() functions below.) If the query could 
** not be executed because a file is missing or has incorrect 
** permissions, this function returns SQLITE_ERROR.
*/
int sqlite_exec(
  sqlite*,                      /* An open database */
  char *sql,                    /* SQL to be executed */
  sqlite_callback,              /* Callback function */
  void *,                       /* 1st argument to callback function */
  char **errmsg                 /* Error msg written here */
);

/*
** Return values for sqlite_exec()
*/
#define SQLITE_OK        0    /* Successful result */
#define SQLITE_ERROR     1    /* SQL error or missing database */
#define SQLITE_INTERNAL  2    /* An internal logic error in SQLite */
#define SQLITE_PERM      3    /* Access permission denied */
#define SQLITE_ABORT     4    /* Callback routine requested an abort */
#define SQLITE_BUSY      5    /* One or more database files are locked */
#define SQLITE_NOMEM     6    /* A malloc() failed */
#define SQLITE_READONLY  7    /* Attempt to write a readonly database */
#define SQLITE_INTERRUPT 8    /* Operation terminated by sqlite_interrupt() */

/* This function causes any pending database operation to abort and
** return at its earliest opportunity.  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.
*/
void sqlite_interrupt(sqlite*);


/* This function returns true if the given input string comprises
** one or more complete SQL statements.
**
** The algorithm is simple.  If the last token other than spaces
** and comments is a semicolon, then return true.  otherwise return
** false.
*/
int sqlite_complete(const char *sql);

/*
** This routine identifies a callback function that is invoked
** whenever an attempt is made to open a database table that is
** currently locked by another process or thread.  If the busy callback
** is NULL, then sqlite_exec() returns SQLITE_BUSY immediately if
** it finds a locked table.  If the busy callback is not NULL, then
** sqlite_exec() invokes the callback with three arguments.  The
** second argument is the name of the locked table and the third
** argument is the number of times the table has been busy.  If the
** busy callback returns 0, then sqlite_exec() immediately returns
** SQLITE_BUSY.  If the callback returns non-zero, then sqlite_exec()
** tries to open the table again and the cycle repeats.
**
** The default busy callback is NULL.
**
** Sqlite is re-entrant, so the busy handler may start a new query. 
** (It is not clear why anyone would every want to do this, but it
** is allowed, in theory.)  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 coredump.
*/
void sqlite_busy_handler(sqlite*, int(*)(void*,const char*,int), void*);

/*
** This routine sets a busy handler that sleeps for a while when a
** table is locked.  The handler will sleep multiple times until 
** at least "ms" milleseconds of sleeping have been done.  After
** "ms" milleseconds of sleeping, the handler returns 0 which
** causes sqlite_exec() to return SQLITE_BUSY.
**
** Calling this routine with an argument less than or equal to zero
** turns off all busy handlers.
*/
void sqlite_busy_timeout(sqlite*, int ms);

/*
** This next routine is really just a wrapper around sqlite_exec().
** 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 malloc(), then returns all of the result after the
** query has finished. 
**
** As an example, suppose the query result where this table:
**
**        Name        | Age
**        -----------------------
**        Alice       | 43
**        Bob         | 28
**        Cindy       | 21
**
** If the 3rd argument were &azResult then after the function returns
** azResult will contain the following data:
**
**        azResult[0] = "Name";
**        azResult[1] = "Age";
**        azResult[2] = "Alice";
**        azResult[3] = "43";
**        azResult[4] = "Bob";
**        azResult[5] = "28";
**        azResult[6] = "Cindy";
**        azResult[7] = "21";
**
** 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).
**
** After the calling function has finished using the result, it should 
** pass the result data pointer to sqlite_free_table() in order to 
** release the memory that was malloc-ed.  Because of the way the 
** malloc() happens, the calling function must not try to call 
** malloc() directly.  Only sqlite_free_table() is able to release 
** the memory properly and safely.
**
** The return value of this routine is the same as from sqlite_exec().
*/
int sqlite_get_table(
  sqlite*,               /* An open database */
  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 */
);

/*
** Call this routine to free the memory that sqlite_get_table() allocated.
*/
void sqlite_free_table(char **result);

/*
** The following routines are wrappers around sqlite_exec() and
** sqlite_get_table().  The only difference between the routines that
** follow and the originals is that the second argument to the 
** routines that follow is really a printf()-style format
** string describing the SQL to be executed.  Arguments to the format
** string appear at the end of the argument list.
**
** All of the usual printf formatting options apply.  In addition, there
** is a "%q" option.  %q 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.  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:
**
**      char *zText = "It's a happy day!";
**
** We can use this text in an SQL statement as follows:
**
**      sqlite_exec_printf(db, "INSERT INTO table VALUES('%q')",
**          callback1, 0, 0, zText);
**
** Because the %q format string is used, the '\'' character in zText
** is escaped and the SQL generated is as follows:
**
**      INSERT INTO table1 VALUES('It''s a happy day!')
**
** This is correct.  Had we used %s instead of %q, the generated SQL
** would have looked like this:
**
**      INSERT INTO table1 VALUES('It's a happy day!');
**
** This second example is an SQL syntax error.  As a general rule you
** should always use %q instead of %s when inserting text into a string 
** literal.
*/
int sqlite_exec_printf(
  sqlite*,                      /* An open database */
  char *sqlFormat,              /* printf-style format string for the SQL */
  sqlite_callback,              /* Callback function */
  void *,                       /* 1st argument to callback function */
  char **errmsg,                /* Error msg written here */
  ...                           /* Arguments to the format string. */
);
int sqlite_exec_vprintf(
  sqlite*,                      /* An open database */
  char *sqlFormat,              /* printf-style format string for the SQL */
  sqlite_callback,              /* Callback function */
  void *,                       /* 1st argument to callback function */
  char **errmsg,                /* Error msg written here */
  va_list ap                    /* Arguments to the format string. */
);
int sqlite_get_table_printf(
  sqlite*,               /* An open database */
  char *sqlFormat,       /* printf-style format string for the SQL */
  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 */
  ...                    /* Arguments to the format string */
);
int sqlite_get_table_vprintf(
  sqlite*,               /* An open database */
  char *sqlFormat,       /* printf-style format string for the SQL */
  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 */
  va_list ap             /* Arguments to the format string */
);


#endif /* _SQLITE_H_ */