Difference between mysql_connect() and mysql_pconnect() PHP
mysql_pconnect() acts very much like mysql_connect() with two major differences.
When connecting using mysql_pconnect() , the function would first try to find a (persistent) link that’s already open with the same host, username and password. If one is found, an identifier for it will be returned instead of opening a new connection.
When connecting using mysql_connect(), the connection to the SQL server will not be closed when the execution of the script ends. Instead, the link will remain open for future use
Note :mysql_close() will not close links established by mysql_pconnect().