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
#思路：①先选出9月份完成试卷>=3的uid；②两表连接，将之前选出的uid作为子查询条件，再根据tag分组计数即可； select tag, count(tag) tag_cnt from exam_record left join examination_info using(exam_id) where uid in (select uid from exam_record where date_format(submit_time,'%Y%m')='202109' group by uid having count(score)>=3) group by tag order by tag_cnt desc
