MySQL datediff 奇怪的结果

Question

我得到 datediff 函数的奇怪结果。对于不同和相同的时间戳为零？

select datediff('2015-04-25 20:37:45','2015-04-25 05:20:00');
+-------------------------------------------------------+
| datediff('2015-04-25 20:37:45','2015-04-25 05:20:00') |
+-------------------------------------------------------+
|                                                     0 |
+-------------------------------------------------------+

select datediff('2015-04-25 20:37:45','2015-04-25 20:37:45');
+-------------------------------------------------------+
| datediff('2015-04-25 20:37:45','2015-04-25 20:37:45') |
+-------------------------------------------------------+
|                                                     0 |
+-------------------------------------------------------+

Answer 1

datediff 将对日期进行计算并找到天数差异，但是你可以使用 timestampdiff对于不同的差异，例如 hour、min 等

mysql> select timestampdiff(hour,'2015-04-25 05:20:00','2015-04-25 20:37:45') as hour;
+------+
| hour |
+------+
|   15 |
+------+
1 row in set (0.00 sec)