题解 | 每类试卷得分前3名

WITH t AS ( SELECT uid, tag, max( score ) AS da, min( score ) AS xiao FROM exam_record left join examination_info using(exam_id)where score is not null GROUP BY 1, 2 order by 2,3 desc ) 
select * from(
SELECT
tag,
uid,
row_number() over ( PARTITION BY tag ORDER BY da DESC, xiao DESC, uid DESC ) AS ranking
FROM
	t
	) tmp where ranking<=3