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
a.university,
count(b.question_id)/count( distinct b.device_id) as avg_answer_num
from
user_profile a
left join question_practice_detail b on a.device_id = b.device_id
where b.device_id is not null
group by a.university
order by a.university
