MySQL 统计一个字段中各值出现次数并按另一字段分组

SELECT  u_name, SUM( CASE u_password WHEN '1' THEN 1 ELSE 0 END ) 'a',SUM( CASE u_password WHEN '2' THEN 1 ELSE 0 END ) 'b', SUM( CASE u_password WHEN '3' THEN 1 ELSE 0 END ) 'c', SUM( CASE u_password WHEN '4' THEN 1 ELSE 0 END ) 'd' FROM `user` GROUP BY u_name HAVING a=1 or b=1 or c=1 or d=1