20.6.11.27 mysql_stmt_store_result()

int mysql_stmt_store_result(MYSQL_STMT *stmt)

Description

Result sets are produced by calling mysql_stmt_execute() to executed prepared statements for SQL statements such as SELECT, SHOW, DESCRIBE, and EXPLAIN. By default, result sets for successfully executed prepared statements are not buffered on the client and mysql_stmt_fetch() fetches them one at a time from the server. To cause the complete result set to be buffered on the client, call mysql_stmt_store_result() after binding data buffers with mysql_stmt_bind_result() and before calling mysql_stmt_fetch() to fetch rows. (For an example, see Section 20.6.11.11, “mysql_stmt_fetch().)

mysql_stmt_store_result() is optional for result set processing, unless you will call mysql_stmt_data_seek(), mysql_stmt_row_seek(), or mysql_stmt_row_tell(). Those functions require a seekable result set.

It is unnecessary to call mysql_stmt_store_result() after executing an SQL statement that does not produce a result set, but if you do, it does not harm or cause any notable performance problem. You can detect whether the statement produced a result set by checking if mysql_stmt_result_metadata() returns NULL. For more information, refer to Section 20.6.11.22, “mysql_stmt_result_metadata().

Note

MySQL does not by default calculate MYSQL_FIELD->max_length for all columns in mysql_stmt_store_result() because calculating this would slow down mysql_stmt_store_result() considerably and most applications do not need max_length. If you want max_length to be updated, you can call mysql_stmt_attr_set(MYSQL_STMT, STMT_ATTR_UPDATE_MAX_LENGTH, &flag) to enable this. See Section 20.6.11.3, “mysql_stmt_attr_set().

Return Values

Zero for success. Nonzero if an error occurred.

Errors

If the application is linked to the embedded server library, runtime error messages will indicate the libmysqld rather than libmysqlclient library, but the solution to the problem is the same as just described.