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

如我们所知，MySQL中TIME字段的范围是从 ‘-838:59:59’ 到 ‘838:59:59’ 。现在，如果TIMEDIFF()函数的输出超过这个范围，那么MySQL将返回 ‘-838:59:59’或‘838:59:59’ 取决于参数的值。

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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)

上述查询显示，如果总差异超出范围，MySQL将返回TIME字段范围的最大或最小限制值。