题解 | 统计每个学校各难度的用户平均刷题数
统计每个学校各难度的用户平均刷题数
https://www.nowcoder.com/practice/5400df085a034f88b2e17941ab338ee8
SELECT university,
difficult_level,
ROUND(COUNT(q.question_id)/COUNT(DISTINCT q.device_id),4) avg_answer_cnt
FROM user_profile u
JOIN question_practice_detail q
ON u.device_id = q.device_id
JOIN question_detail qd
ON q.question_id = qd.question_id
GROUP BY university,difficult_level
ORDER BY university,difficult_level
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