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
up.university,
qd.difficult_level,
count(qpd.question_id) / count(distinct up.device_id) as avg_answer_cnt
from
question_practice_detail as qpd
inner join user_profile as up on qpd.device_id = up.device_id
inner join question_detail as qd on qd.question_id = qpd.question_id
group by
university,
difficult_level