mysql 的条件判断语句

UPDATE tablename SET `noids`=(CASE `noids` WHEN ',000' THEN ',".$noid."' ELSE concat(noids,',".$value['noid']."') END) WHERE `userid`='".$value['userid']."' AND `uid`='".$row['uid']."' and find_in_set('".$value['noid']."',`noids`)=0";