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 p.university,m.difficult_level,
round(count(m.question_id)/count(distinct(p.device_id)),4) as avg_answer_cnt
from user_profile p
join question_practice_detail t
on p.device_id=t.device_id
join question_detail m
on t.question_id = m.question_id
group by university,m.difficult_level
和上一题一样
不同的是count(m.question_id)/count(distinct(p.device_id))
用了question_id
查看6道真题和解析