capi3ref.tcl

一个小型的嵌入式数据库

 Assuming no other intervening sqlite3_* API calls are made, the error
 code returned by this function is associated with the same error as
 the strings returned by sqlite3_errmsg() and sqlite3_errmsg16().
} {}

api {} {
const char *sqlite3_errmsg(sqlite3*);
const void *sqlite3_errmsg16(sqlite3*);
} {
 Return a pointer to a UTF-8 encoded string (sqlite3_errmsg)
 or a UTF-16 encoded string (sqlite3_errmsg16) describing in English the
 error condition for the most recent sqlite3_* API call. The returned
 string is always terminated by an 0x00 byte.

 The string "not an error" is returned when the most recent API call was
 successful.
}

api {} {
int sqlite3_exec(
  sqlite3*,                     /* An open database */
  const char *sql,              /* SQL to be executed */
  sqlite_callback,              /* Callback function */
  void *,                       /* 1st argument to callback function */
  char **errmsg                 /* Error msg written here */
);
} {
 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 argument 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 sqlite3_exec() function returns the SQLITE_ABORT.

 The 4th argument is an arbitrary pointer that is passed
 to the callback function as its first argument.

 The 2nd argument to the callback function is the number of
 columns in the query result.  The 3rd argument to the callback
 is an array of strings holding the values for each column.
 The 4th argument to the callback 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.  The calling function
 is responsible for freeing the memory that holds the error
 message.   Use sqlite3_free() for this.  If errmsg==NULL,
 then no error message is ever written.

 The return value is is SQLITE_OK if there are no errors and
 some other return code if there is an error.  The particular
 return value depends on the type of error. 

 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 sqlite3_busy_handler()
 and sqlite3_busy_timeout() functions.)
} {}

api {} {
int sqlite3_finalize(sqlite3_stmt *pStmt);
} {
 The sqlite3_finalize() function is called to delete a prepared
 SQL statement obtained by a previous call to sqlite3_prepare()
 or sqlite3_prepare16(). If the statement was executed successfully, or
 not executed at all, then SQLITE_OK is returned. If execution of the
 statement failed then an error code is returned. 

 All prepared statements must finalized before sqlite3_close() is
 called or else the close will fail with a return code of SQLITE_BUSY.

 This routine can be called at any point during the execution of the
 virtual machine.  If the virtual machine has not completed execution
 when this routine is called, that is like encountering an error or
 an interrupt.  (See sqlite3_interrupt().)  Incomplete updates may be
 rolled back and transactions canceled,  depending on the circumstances,
 and the result code returned will be SQLITE_ABORT.
}

api {} {
void sqlite3_free(char *z);
} {
 Use this routine to free memory obtained from 
 sqlite3_mprintf() or sqlite3_vmprintf().
}

api {} {
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);
} {
 This next routine is really just a wrapper around sqlite3_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:

 <pre>
        Name        | Age
        -----------------------
        Alice       | 43
        Bob         | 28
        Cindy       | 21
 </pre>

 If the 3rd argument were &azResult then after the function returns
 azResult will contain the following data:

 <pre>
        azResult[0] = "Name";
        azResult[1] = "Age";
        azResult[2] = "Alice";
        azResult[3] = "43";
        azResult[4] = "Bob";
        azResult[5] = "28";
        azResult[6] = "Cindy";
        azResult[7] = "21";
 </pre>

 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 sqlite3_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 sqlite3_free_table() is able to release 
 the memory properly and safely.

 The return value of this routine is the same as from sqlite3_exec().
}

api {sqlite3_interrupt} {
 void sqlite3_interrupt(sqlite3*);
} {
 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.
} {}

api {} {
long long int sqlite3_last_insert_rowid(sqlite3*);
} {
 Each entry in an SQLite table has a unique integer key.  (The key is
 the value of the INTEGER PRIMARY KEY column if there is such a column,
 otherwise the key is generated at random.  The unique key is always
 available as the ROWID, OID, or _ROWID_ column.)  This routine
 returns the integer key of the most recent insert in the database.

 This function is similar to the mysql_insert_id() function from MySQL.
} {}

api {} {
char *sqlite3_mprintf(const char*,...);
char *sqlite3_vmprintf(const char*, va_list);
} {
 These routines are variants of the "sprintf()" from the
 standard C library.  The resulting string is written into memory
 obtained from malloc() so that there is never a possibility of buffer
 overflow.  These routines also implement some additional formatting
 options that are useful for constructing SQL statements.

 The strings returned by these routines should be freed by calling
 sqlite3_free().

 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:

 <blockquote><pre>
  char *zText = "It's a happy day!";
 </pre></blockquote>

 One can use this text in an SQL statement as follows:

 <blockquote><pre>
  sqlite3_exec_printf(db, "INSERT INTO table VALUES('%q')",
       callback1, 0, 0, zText);
  </pre></blockquote>

 Because the %q format string is used, the '\\'' character in zText
 is escaped and the SQL generated is as follows:

 <blockquote><pre>
  INSERT INTO table1 VALUES('It''s a happy day!')
 </pre></blockquote>

 This is correct.  Had we used %s instead of %q, the generated SQL
 would have looked like this:

  <blockquote><pre>
  INSERT INTO table1 VALUES('It's a happy day!');
  </pre></blockquote>

 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.
} {}

api {} {
int sqlite3_open(
  const char *filename,   /* Database filename (UTF-8) */
  sqlite3 **ppDb          /* OUT: SQLite db handle */
);
int sqlite3_open16(
  const void *filename,   /* Database filename (UTF-16) */
  sqlite3 **ppDb          /* OUT: SQLite db handle */
);
} {
 Open the sqlite database file "filename".  The "filename" is UTF-8
 encoded for sqlite3_open() and UTF-16 encoded in the native byte order
 for sqlite3_open16().  An sqlite3* handle is returned in *ppDb, even
 if an error occurs. If the database is opened (or created) successfully,
 then SQLITE_OK is returned. Otherwise an error code is returned. The
 sqlite3_errmsg() or sqlite3_errmsg16()  routines can be used to obtain
 an English language description of the error.

 If the database file does not exist, then a new database will be created
 as needed.
 The encoding for the database will be UTF-8 if sqlite3_open() is called and
 UTF-16 if sqlite3_open16 is used.

 Whether or not an error occurs when it is opened, resources associated
 with the sqlite3* handle should be released by passing it to
 sqlite3_close() when it is no longer required.
}

api {} {
int sqlite3_prepare(
  sqlite3 *db,            /* Database handle */
  const char *zSql,       /* SQL statement, UTF-8 encoded */
  int nBytes,             /* Length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const char **pzTail     /* OUT: Pointer to unused portion of zSql */
);
int sqlite3_prepare16(
  sqlite3 *db,            /* Database handle */
  const void *zSql,       /* SQL statement, UTF-16 encoded */
  int nBytes,             /* Length of zSql in bytes. */
  sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  const void **pzTail     /* OUT: Pointer to unused portion of zSql */
);
} {
 To execute an SQL query, it must first be compiled into a byte-code
 program using one of the following routines. The only difference between
 them is that the second argument, specifying the SQL statement to
 compile, is assumed to be encoded in UTF-8 for the sqlite3_prepare()
 function and UTF-16 for sqlite3_prepare16().

 The first argument "db" is an SQLite database handle. The second
 argument "zSql" is the statement to be compiled, encoded as either
 UTF-8 or UTF-16 (see above). If the next argument, "nBytes", is less
 than zero, then zSql is read up to the first nul terminator.  If
 "nBytes" is not less than zero, then it is the length of the string zSql
 in bytes (not characters).

 *pzTail is made to point to the first byte past the end of the first
 SQL statement in zSql.  This routine only compiles the first statement
 in zSql, so *pzTail is left pointing to what remains uncompiled.