题解 | 统计每个学校各难度的用户平均刷题数
统计每个学校各难度的用户平均刷题数
https://www.nowcoder.com/practice/5400df085a034f88b2e17941ab338ee8
select
u.university,
qd.difficult_level,
round(count(qpd.question_id)/count(distinct u.device_id),4) as avg_answer_cnt
from user_profile u
join question_practice_detail qpd
on u.device_id=qpd.device_id
join question_detail qd
on qpd.question_id=qd.question_id
group by u.university,qd.difficult_level
order by u.university
