题解 | #每类试卷得分前3名#

SELECT *
FROM (
     SELECT tag                                                                                    AS tid,
            uid,
            ROW_NUMBER() OVER (PARTITION BY tag ORDER BY MAX(score) DESC,MIN(score) DESC,uid DESC) AS ranking
     FROM examination_info a JOIN exam_record b USING (exam_id)
     GROUP BY tag, uid
     ) aa
WHERE ranking <= 3