题解 | #统计复旦用户8月练题情况#
统计复旦用户8月练题情况
https://www.nowcoder.com/practice/53235096538a456b9220fce120c062b3
SELECT
up.device_id,up.university,
COUNT(question_id) AS question_cnt,
SUM(if(qpd.result='right',1,0)) AS right_question_cnt
FROM
user_profile AS up
LEFT JOIN
question_practice_detail AS qpd
ON
qpd.device_id=up.device_id
WHERE
up.university='复旦大学'AND MONTH(qpd.date)=8
#感觉MONTH条件写在这个位置更好一点
GROUP BY
up.device_id;
#这是我根据大佬写的自己修改的，这样看起来更清晰一点。