mysql_unbuffered_query sends the SQL query query to MySQL without automatically fetching and buffering the result rows as mysql_query does. This saves a considerable amount of memory with SQL queries that produce large result sets, and you can start working on the result set immediately after the first row has been retrieved as you don't have to wait until the complete SQL query has been performed. To use mysql_unbuffered_query while multiple database connections are open, you must specify the optional parameter link_identifier to identify which connection you want to use.
The SQL query to execute.
Data inside the query should be properly escaped.
The MySQL connection. If the link identifier is not specified, the last link opened by mysql_connect is assumed. If no such link is found, it will try to create one as if mysql_connect had been called with no arguments. If no connection is found or established, an E_WARNING level error is generated.
For SELECT, SHOW, DESCRIBE or EXPLAIN statements, mysql_unbuffered_query returns a resource on success, or false on error.
For other type of SQL statements, UPDATE, DELETE, DROP, etc, mysql_unbuffered_query returns true on success or false on error.
The benefits of mysql_unbuffered_query come at a cost: you cannot use mysql_num_rows and mysql_data_seek on a result set returned from mysql_unbuffered_query, until all rows are fetched. You also have to fetch all result rows from an unbuffered SQL query before you can send a new SQL query to MySQL, using the same link_identifier.