题解 | #删除记录（二）#
删除记录（二）
https://www.nowcoder.com/practice/964c9f7fffbb4ab18b507cfed4111b4a
delete from exam_record where submit_time is null or timestampdiff(minute,start_time,submit_time)<5 order by start_time limit 3;
分解筛选器：
1、筛选未完成的 ：submit_time is null
没有用括号的or 是一个大or
2、筛选三个左大时间最早并且作答时间小于5分钟的
