Managing & Using MySQL, 2nd Edition

Name

mysql_pconnect

Synopsis

cresource mysql_pconnect([string hostname [, string username [, string password]]])

Used to establish or re-establish a connection to the MySQL DBMS. The function returns a connection resource handle on success that can be used to access databases through subsequent function calls. The function returns false on failure. The three parameters are identical to the first three parameters of mysql_connect( ).

This function should be called only once with the same parameters in a script: any subsequent calls to mysql_pconnect( ) in the same script with the same parameters return the same connection handle. Indeed, connections created with mysql_pconnect( ) are often reused across several scripts: the p stands for persistent, which means that after the script ends, the connection is kept in a pool. The connection can then be reused by any other script that requires a connection with the same hostname, username, and password.

Connections in the pool that remain unused are closed to save resources. How long a connection can remain unused is a MySQL parameter and is set to a default of five seconds. This can be changed with the --set-variable connect_timeout parameter to safe_mysqld.

Persistent connections are available only through a PHP module that is integrated into a web server. See Chapter 11 for details.

Example

<?php $query = "SELECT * FROM presents"; $connection = mysql_pconnect("localhost", "fred", "shhh"); mysql_select_db("wedding", $connection); $result ...