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_cnt
from user_profile up
join question_practice_detail qpd
on up.device_id = qpd.device_id
join question_detail qd
on qpd.question_id = qd.question_id
where up.university = '山东大学'
group by qd.difficult_level;
不建议写那么大，可以从小出发更容易