php mysqlのdatetime型をformat

echo date('D, d M Y H:i:s', strtotime('2011-12-06 14:51:12');

>Tue, 06 Dec 2011 14:51:12

echo date('r', strtotime('2011-12-06 14:51:12');

>Tue, 06 Dec 2011 14:51:12 +0900

http://php.net/manual/ja/function.date.php