mysql_stmt_attr_set()

You can call the mysql_stmt_attr_set() function to set an attribute value for a prepared statement.

Syntax

my_bool
mysql_stmt_attr_set(MYSQL_STMT *stmt,
                    enum enum_stmt_attr_type option,
                    const void *arg)

Arguments

• option: the option to be set.

• arg: the value of the option. arg should point to a variable of the desired attribute value. The following table describes the variable types.

  Option	Parameter type	Description
  STMT_ATTR_UPDATE_MAX_LENGTH	my_bool *	If it is set to 1, it will cause mysql_stmt_store_result() to update the metadata MYSQL_FIELD->max_length value.
  STMT_ATTR_CURSOR_TYPE	unsigned long *	The type of cursor to be opened for the statement when mysql_stmt_execute() is called. *arg can be CURSOR_TYPE_NO_CURSOR (default value) or CURSOR_TYPE_READ_ONLY.
  STMT_ATTR_PREFETCH_ROWS	unsigned long *	The number of rows fetched at a time from the server when a cursor is used. *arg ranges from 1 to the maximum value of unsigned long. Default value: 1

  If you use the STMT_ATTR_CURSOR_TYPE option together with CURSOR_TYPE_READ_ONLY, a cursor is opened for the statement when you invoke mysql_stmt_execute(). If a cursor is already opened from a previous mysql_stmt_execute() call, mysql_stmt_reset() closes the cursor before opening a new one. mysql_stmt_reset() also closes open cursors before preparing a statement for re-execution.

  mysql_stmt_free_result() can close any open cursor.

Return values

0 is returned for an execution success, and a non-zero value is returned if the option is unknown.

Errors

None.

Notes

You can call the option multiple times to set several options.

If a cursor is opened for a prepared statement, you do not need to call mysql_stmt_store_result(), because that function causes the result set to be buffered on the client.