How to convert date formate in php

<?php
 $old_date = date("2012-11-15 03:25:42");  here date formate is  (yyyy-mm-dd h:m:s)
 $middle = strtotime($old_date);
$new_date = date('l , F d , Y', $middle);
echo $new_date; ?>

output :
                Monday , July 02 , 2012
it will print out put of this formate. and you can change in the date function to change your choice date formate.