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
B.university,
C.difficult_level,
COUNT(A.question_id) /COUNT(DISTINCT A.device_id) as avg_answer_cnt
FROM
question_practice_detail A
INNER JOIN user_profile B ON A.device_id = B.device_id
LEFT JOIN question_detail C
ON A.question_id = C.question_id
GROUP BY
B.university,
C.difficult_level;
