timediff的意外结果

Question

timediff功能无法正常工作.在下面的例子中,我试图计算1年期间的差异.

mysql>SELECT 366*24*60*60 AS expected;
+----------+
| expected |
+----------+
| 31622400 | 
+----------+
1 row in set (0.00 sec)

mysql>SELECT ABS(UNIX_TIMESTAMP('2000:01:01 00:00:00') - UNIX_TIMESTAMP('2001:01:01 00:00:00'));
+------------------------------------------------------------------------------------+
| ABS(UNIX_TIMESTAMP('2000:01:01 00:00:00') - UNIX_TIMESTAMP('2001:01:01 00:00:00')) |
+------------------------------------------------------------------------------------+
|                                                                           31622400 | 
+------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql>SELECT TIME_TO_SEC(TIMEDIFF('2000:01:01 00:00:00', '2001:01:01 00:00:00'));
+---------------------------------------------------------------------+
| TIME_TO_SEC(TIMEDIFF('2000:01:01 00:00:00', '2001:01:01 00:00:00')) |
+---------------------------------------------------------------------+
|                                                            -3020399 | 
+---------------------------------------------------------------------+
1 row in set, 1 warning (0.00 sec)

Warning (Code 1292): Truncated incorrect time value: '-8784:00:00'

Answer 1

编辑:您使用的是哪个版本的MySQL？它至少在5.0.22上工作正常.我刚刚运行了这个查询.看这里

 mysql> SELECT TIME_TO_SEC(TIMEDIFF('2000:01:01 00:00:00', '2001:01:01 00:00:00'));
 +---------------------------------------------------------------------+
 | TIME_TO_SEC(TIMEDIFF('2000:01:01 00:00:00', '2001:01:01 00:00:00')) |
 +---------------------------------------------------------------------+
 |                                                           -31622400 |
 +---------------------------------------------------------------------+
 1 row in set (0.00 sec)

你看到了吗？这可能是截断问题,因为时间范围远小于您拥有的日期差异.

原始答案

用这个

    SELECT TIMESTAMPDIFF(SECOND,'2000:01:01 00:00:00', '2001:01:01 00:00:00');
    +--------------------------------------------------------------------+
    | TIMESTAMPDIFF(SECOND,'2000:01:01 00:00:00', '2001:01:01 00:00:00') |
    +--------------------------------------------------------------------+
    |                                                           31622400 |
    +--------------------------------------------------------------------+

问题是你正试图将负时间转换为秒时间.交换变量将完成这项工作.

    SELECT TIME_TO_SEC(TIMEDIFF('2001:01:01 00:00:00','2000:01:01 00:00:00'));
    +--------------------------------------------------------------------+
    | TIME_TO_SEC(TIMEDIFF('2001:01:01 00:00:00','2000:01:01 00:00:00')) |
    +--------------------------------------------------------------------+
    |                                                           31622400 |
    +--------------------------------------------------------------------+