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
要注意group by分组这一行不能少 select a.university,count(b.result)/count(distinct b.device_id) as avg_answer_cnt from user_profile as a join question_practice_detail as b on a.device_id=b.device_id group by a.university order by a.university asc;
