题解 | #统计每个学校的答过题的用户的平均答题数#左连接
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
SELECT
up.university,
ROUND(COUNT(qpd.question_id) / COUNT(DISTINCT qpd.device_id), 4) AS avg_answer_cnt
FROM
user_profile AS up
LEFT JOIN
question_practice_detail AS qpd
ON
up.device_id = qpd.device_id
GROUP BY
up.university;