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
p.university,
q.difficult_level,
count(d.question_id) / count(distinct d.device_id) as avg_answer_cnt
from
user_profile p
join question_practice_detail d on d.device_id = p.device_id
join question_detail q on d.question_id = q.question_id
where p.university = '山东大学'
group by
p.university,
q.difficult_level
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