题解 | 每份试卷每月作答数和截止当月的作答总数。
每份试卷每月作答数和截止当月的作答总数。
https://www.nowcoder.com/practice/5f1cbe74c682485aa73e4c2b30f04a62
select
*,
sum(month_cnt) over(partition by exam_id order by start_month ROWS between unbounded preceding and current row)
from
(
select
exam_id,
date_format(start_time,'%Y%m') as start_month,
count(start_time) as month_cnt
from exam_record er
group by er.exam_id, date_format(start_time,'%Y%m')
) t
order by exam_id
腾讯成长空间 5958人发布
投递中国移动等公司6个岗位