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?tpId=199&tqId=1975674&sourceUrl=%2Fexam%2Foj%3FquestionJobId%3D10%26subTabName%3Donline_coding_page
select up.university,avg(answer_cnt) avg_answer_cnt from user_profile up left join (select device_id,count( question_id) answer_cnt from question_practice_detail group by device_id)qpd on up.device_id = qpd.device_id where answer_cnt is not null group by up.university order by up.university
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