如果 MySQL TIMEDIFF() 函数的输出超出 TIME 字段的范围值会发生什么？

我们知道MySQL中TIME字段的范围是‘-838:59:59’到‘838:59:59’。现在，如果 TIMEDIFF() 函数的输出超出此范围，则 MySQL 将返回 ‘-838:59:59’ 或 ‘838:59:59’，具体取决于参数的值。

示例

mysql> Select TIMEDIFF('2017-09-01 03:05:45','2017-10-22 03:05:45')AS 'Out of Range TIME Difference';
+------------------------------+
| Out of Range TIME Difference |
+------------------------------+
| -838:59:59                   |
+------------------------------+
1 row in set, 1 warning (0.00 sec)
mysql> Select TIMEDIFF('2017-10-22 04:05:45','2017-09-01 03:05:45')AS 'Out of Range TIME Difference';
+------------------------------+
| Out of Range TIME Difference |
+------------------------------+
| 838:59:59                    |
+------------------------------+
1 row in set, 1 warning (0.01 sec)

上面的查询表明，如果总差值超出范围，MySQL 将返回 TIME 字段范围的最大或最小限制值。