题解 | #删除记录（二）#
删除记录（二）
http://www.nowcoder.com/practice/964c9f7fffbb4ab18b507cfed4111b4a
order by
limit
delete from exam_record where submit_time is NULL&nbs***bsp;TIMESTAMPDIFF(minute,start_time,submit_time) < 5 order by start_time asc limit 3
