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 b.university as university ,count(1)/count(distinct a.device_id) as avg_answer_cnt from question_practice_detail a left join user_profile b on a.device_id = b.device_id group by 1
