题解 | 统计每个学校的答过题的用户的平均答题数
统计每个学校的答过题的用户的平均答题数
https://www.nowcoder.com/practice/88aa923a9a674253b861a8fa56bac8e5
select
university,
count(1)/count(distinct a.device_id) as avg_answer_cnt
from
question_practice_detail as a
left join user_profile as b
on a.device_id = b.device_id
group by 1
order by 1
count(1)是每个大学的总答题数
count(distinct a.device_id)是去重复用户后的答题人数
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