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 up.university,qd.difficult_level,format(count(*) / count(distinct qpd.device_id),4) as avg_answer_cnt
from user_profile up
inner join question_practice_detail qpd on up.device_id = qpd.device_id
left join question_detail qd on qpd.question_id = qd.question_id
group by up.university,qd.difficult_level;

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