Understanding of the mysql_pconnect() function

Definition and usage About the mysql_pconnect function in mysql, which is used to open a persistent connection to the MySQL server. mysql_pconnect() and mysql_connect() are very similar, but have two main differences: When connecting, this function first tries to find a (persistent) connection that is already open on the same host with the same username and password. If found, it returns the connection ID without opening a new connection. Secondly, when the script completes execution, the connection to the mysql server will not be closed, this connection will remain open for future use (mysql_close() will not close the connection established by mysql_pconnect()).

Grammar mysql_pconnect(server,user,pwd,clientflag)

Parameter Description server Optional. Specifies the server to connect to. Can include a port number, such as "hostname:port", or a path to a local socket, such as ":/path/to/socket" for localhost. If the PHP directive mysql.default_host is not defined (the default), the default value is 'localhost:3306'. user optional. username. The default value is the username of the server process owner. pwd Optional. password. The default value is an empty password. clientflag Optional. The client_flags parameter can be a combination of the following constants:

Return value If successful, return a MySQL persistent connection identifier, otherwise return FALSE.

Tips and Notes Note: The optional clientflag parameter is available since PHP version 4.3.0. Tip: To create a non-persistent connection, use the mysql_connect() function.

Example:

<?php
//mysql_pconnect示例
$con = mysql_pconnect("localhost","mysql_user","mysql_pwd");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }
?>