Once you can get the date into as a timestamp, you can use the date() function to do any crazy format you need. To get your sql value into timestamp format, you will want to use the mktime function. Example:
$sqldate = '2001-04-18';
$dateArray = explode("_", $sqldate);
$timestamp = mktime(0,0,0, $dateArray[1],$dateArray[2],$dateArray[0]);
echo date ("l, F j, Y", $timestamp);
It might be a good idea to add some checks for a time after the date, which would break this example code.