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
user_profile.university,
count(question_practice_detail.question_id) / count(distinct(question_practice_detail.device_id) )as avg_answer_cnt
from user_profile join question_practice_detail on user_profile.device_id = question_practice_detail.device_id
group by user_profile.university
user_profile.university,
count(question_practice_detail.question_id) / count(distinct(question_practice_detail.device_id) )as avg_answer_cnt
from user_profile join question_practice_detail on user_profile.device_id = question_practice_detail.device_id
group by user_profile.university