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 '山东大学' AS university, difficult_level, ROUND(COUNT(qpd.question_id)/COUNT(DISTINCT qpd.device_id),4) AS avg_answer_cnt FROM question_practice_detail AS qpd INNER JOIN user_profile AS up ON up.device_id = qpd.device_id AND university = '山东大学' INNER JOIN question_detail AS qd ON qd.question_id = qpd.question_id GROUP BY difficult_level
