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
http://www.nowcoder.com/practice/88aa923a9a674253b861a8fa56bac8e5
考点
- group by
- order by
- distinct
- round
- count
select u.university,round(count(q.device_id)/(count(distinct q.device_id)),4)
as avg_answer_cnt from user_profile u inner join question_practice_detail q
on u.device_id = q.device_id group by u.university
order by u.university;
