mysql> SELECT DATE_FORMAT('2009-10-04 22:23:00', '%Y%m%d%H%i%s');
-> 20091004222300
mysql> SELECT DATE_FORMAT('2009-10-04', '%Y%m%d%H%i%s');
-> 20091004000000
mysql> SELECT DATE_FORMAT('2009-10-04', GET_FORMAT(DATETIME,'INTERNAL'));
-> 20091004000000