UNION排序 | #每个题目和每份试卷被作答的人数和次数#
每个题目和每份试卷被作答的人数和次数
https://www.nowcoder.com/practice/203d0aed8928429a8978185d9a03babc
select * from (select exam_id tid, count(distinct uid) uv, count(1) pv from exam_record group by exam_id order by uv desc, pv desc) t1 union select * from (select question_id tid, count(distinct uid) uv, count(1) pv from practice_record group by question_id order by uv desc, pv desc) t2;
两个表排序后联合，需要额外添加一层select *。
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