三步走策略: sql求出用户总积分 SELECT g.user_id, sum( CASE WHEN g.type = 'reduce' THEN - grade_num ELSE grade_num END ) AS totalPoint FROM grade_info g GROUP BY g.user_id sql求出用户最大积分 select s1.totalPoint as maxPoint from (SELECT g.user_id, sum( CASE WHEN g.type = 'reduce' THEN -...