mysql合并两个更新语句 UPDATE CommunityAnswer SET agreed = agreed - 1 WHERE agreed 0 AND id = OLDanswerid AND 1 = OLDopinion; UPDATE CommunityAnswer SET opposed = opposed - 1 WHERE opposed 0 AND id = OLDan

UPDATE CommunityAnswer SET agreed = CASE WHEN agreed > 0 AND id = OLD.answerid AND 1 = OLD.opinion THEN agreed - 1 ELSE agreed END, opposed = CASE WHEN opposed > 0 AND id = OLD.answerid AND 0 = OLD.opinion THEN opposed - 1 ELSE opposed END;