题解 | #统计每个学校的答过题的用户的平均答题数#
统计每个学校的答过题的用户的平均答题数
https://www.nowcoder.com/practice/88aa923a9a674253b861a8fa56bac8e5
select university, round( count(q.question_id) / count(distinct q.device_id), 4 ) as avg_answer_cnt from user_profile u right join question_practice_detail q on u.device_id = q.device_id group by university order by university 题干重点:答过题的平均用户答题数,B表是答题用户和答题明细,所以以B表为主表进行查询