題解 | #統(tǒng)計(jì)每個(gè)學(xué)校的答過題的用戶的平均答題數(shù)#
統(tǒng)計(jì)每個(gè)學(xué)校的答過題的用戶的平均答題數(shù)
http://fangfengwang8.cn/practice/88aa923a9a674253b861a8fa56bac8e5
select university, count(qp.question_id)/count(distinct(qp.device_id)) avg_answer_cnt from question_practice_detail qp,user_profile up where qp.device_id=up.device_id group by up.university order by up.university asc