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,
sum(date) / count(a.device_id)
from
user_profile a,
(
select
device_id,
COUNT(question_id) date
from
question_practice_detail
group by
device_id
) b
where
a.device_id = b.device_id
group by
university
order by
university;
