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