题解 | #月均完成试卷数不小于3的用户爱作答的类别#
月均完成试卷数不小于3的用户爱作答的类别
https://www.nowcoder.com/practice/b1d13efcfa0c4ecea517afbdb9090845
SELECT
tag,count(r.exam_id) as tag_cnt # 只需作答即可，所以count(exam_id)
FROM
exam_record r
LEFT JOIN examination_info i
ON r.exam_id=i.exam_id
WHERE uid in # 对用户进行过滤，满足月均完成不小于3
(SELECT uid FROM exam_record r
WHERE
month (submit_time) = 09
GROUP by
uid
HAVING
count(score)>=3)
GROUP by tag
ORDER BY tag_cnt desc
