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 ASC,
qd.difficult_level ASC;
