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