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,count(u.device_id)/count(distinct u.device_id) as avg_answer_cnt from user_profile u,question_practice_detail q where u.device_id=q.device_id group by university
