mysql_use_result() - mysql/mysql.h

 After invoking mysql_query() or
        mysql_real_query(), you must
        call mysql_store_result() or
        mysql_use_result() for every
        statement that successfully produces a result set
        (SELECT,
        SHOW,
        DESCRIBE,
        EXPLAIN,
        CHECK TABLE, and so forth). You
        must also call
        mysql_free_result() after you
        are done with the result set.mysql_query()mysql_query()mysql_real_query()mysql_real_query()mysql_store_result()mysql_store_result()mysql_use_result()mysql_use_result()SELECTSELECTSHOWSHOWDESCRIBEDESCRIBEEXPLAINEXPLAINCHECK TABLECHECK TABLEmysql_free_result()mysql_free_result()mysql_use_result() initiates a
        result set retrieval but does not actually read the result set
        into the client like
        mysql_store_result() does.
        Instead, each row must be retrieved individually by making calls
        to mysql_fetch_row(). This reads
        the result of a query directly from the server without storing
        it in a temporary table or local buffer, which is somewhat
        faster and uses much less memory than
        mysql_store_result(). The client
        allocates memory only for the current row and a communication
        buffer that may grow up to
        max_allowed_packet bytes.mysql_use_result()mysql_use_result()mysql_store_result()mysql_store_result()mysql_fetch_row()mysql_fetch_row()mysql_store_result()mysql_store_result()max_allowed_packetmax_allowed_packetOn the other hand, you should not use
        mysql_use_result() for locking
        reads if you are doing a lot of processing for each row on the
        client side, or if the output is sent to a screen on which the
        user may type a ^S (stop scroll). This ties
        up the server and prevent other threads from updating any tables
        from which the data is being fetched.mysql_use_result()mysql_use_result()^SWhen using mysql_use_result(),
        you must execute
        mysql_fetch_row() until a
        NULL value is returned, otherwise, the
        unfetched rows are returned as part of the result set for your
        next query. The C API gives the error Commands out of
        sync; you can't run this command now if you forget to
        do this!mysql_use_result()mysql_use_result()mysql_fetch_row()mysql_fetch_row()NULLCommands out of
        sync; you can't run this command nowYou may not use
        mysql_data_seek(),
        mysql_row_seek(),
        mysql_row_tell(),
        mysql_num_rows(), or
        mysql_affected_rows() with a
        result returned from
        mysql_use_result(), nor may you
        issue other queries until
        mysql_use_result() has finished.
        (However, after you have fetched all the rows,
        mysql_num_rows() accurately
        returns the number of rows fetched.)mysql_data_seek()mysql_data_seek()mysql_row_seek()mysql_row_seek()mysql_row_tell()mysql_row_tell()mysql_num_rows()mysql_num_rows()mysql_affected_rows()mysql_affected_rows()mysql_use_result()mysql_use_result()mysql_use_result()mysql_use_result()mysql_num_rows()mysql_num_rows()You must call
        mysql_free_result() once you are
        done with the result set.mysql_free_result()mysql_free_result()When using the libmysqld embedded server, the
        memory benefits are essentially lost because memory usage
        incrementally increases with each row retrieved until
        mysql_free_result() is called.libmysqldmysql_free_result()mysql_free_result()

Syntax

MYSQL_RES *mysql_use_result(MYSQL *mysql)

Example

Output / Return Value

 A MYSQL_RES result structure.
        NULL if an error occurred.MYSQL_RESNULL

Limitations

Alternatives / See Also

Reference