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
,count(question_id)/count(distinct(question_practice_detail.device_id))
from question_practice_detail
left join(
select device_id,university
from user_profile
) a
on question_practice_detail.device_id = a.device_id
group by university;
