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(*)/count(distinct u.device_id),4) avg_answer_cnt # count(*)代表group by分组之后 每个组含有多少行,然后计数 from user_profile u join question_practice_detail q on u.device_id = q.device_id group by 1 order by university