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 t1.university,count(t1.university)/count(distinct(t2.device_id)) avg_answer_cnt from user_profile t1,question_practice_detail t2 where t1.device_id=t2.device_id group by t1.university
