题解 | #删除记录（二）#
删除记录（二）
https://www.nowcoder.com/practice/964c9f7fffbb4ab18b507cfed4111b4a
本题思路较前一题主要增加了对特定位置数据的删除，需进一步使用limit函数：
delete from exam_record where timestampdiff(minute,start_time,submit_time) < 5 or score is null order by start_time asc limit 3
