题解 | #统计每个用户的平均刷题数#
统计每个用户的平均刷题数
https://www.nowcoder.com/practice/f4714f7529404679b7f8909c96299ac4
select
u.university,q2.difficult_level,(count(q1.question_id)/count(distinct(q1.device_id))) as avg_answer
from
user_profile as u
inner join
question_practice_detail as q1
on
u.device_id = q1.device_id
inner join
question_detail as q2
on
q1.question_id=q2.question_id
group by u.university, q2.difficult_level
having u.university = "山东大学"
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