题解 | #获得积分最多的人(二)#

SELECT
    t.id,
    u.NAME,
    t.sum 
FROM
    ( SELECT user_id AS id, sum( grade_num ) AS sum FROM grade_info GROUP BY user_id ) AS t
    INNER JOIN user u ON u.id = t.id 
WHERE
    sum = ( SELECT max( b.a ) FROM ( SELECT sum( grade_num ) AS a FROM grade_info GROUP BY user_id ) b) 
  ORDER BY t.id