题解 | #删除记录（二）#
删除记录（二）
https://www.nowcoder.com/practice/964c9f7fffbb4ab18b507cfed4111b4a
本题主要难点在于首先是排序asc降序排序，其次用到limit限制符，还有就是timestampdiiff 用minute为单位必须要<5而不能<=5，因为有些时间间隔超出5分钟比如5分半也会按照5分计算，就与题目不符合了
delete from
exam_record
where
timestampdiff (minute, start_time, submit_time) < 5
or submit_time is null
order by
start_time asc
limit
3
