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
university,difficult_level,round(count(q.question_id)/count(distinct u.device_id),4)
from
question_practice_detail q
left join user_profile u on u.device_id =q.device_id
left join question_detail qd on q.question_id=qd.question_id
group by university,difficult_level
