题解 | #近三个月未完成试卷数为0的用户完成情况#
近三个月未完成试卷数为0的用户完成情况
https://www.nowcoder.com/practice/4a3acb02b34a4ecf9045cefbc05453fa
select uid,count(score) as exam_complete_cnt from( select *, dense_rank()over(partition by uid order by date_format(start_time,'%Y%m') desc) as rk from exam_record) a where rk <= 3 group by uid having count(start_time) = count(submit_time) order by exam_complete_cnt desc,uid desc
要用dense_rank()而不是row_unmber()，因为最近三个月的记录相同月份也要记录在内。
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