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,
round(count(qd.difficult_level) / count(distinct up.device_id),4) as avg_answer_cnt
from
user_profile as up
inner join question_practice_detail as qpd on up.device_id = qpd.device_id
left join question_detail as qd on qpd.question_id = qd.question_id
group by
up.university,
qd.difficult_level

