题解 | #更新记录（二）#
更新记录（二）
http://www.nowcoder.com/practice/0c2e81c6b62e4a0f848fa7693291defc
**判空 用is null 不是 = null **
update exam_record set submit_time = '2099-01-01 00:00:00', score = 0
where start_time < '2021-09-01 00:00:00' and submit_time is null;
