当使用now()进行简单的数学计算时...
mysql>
select cdrstatuschangets from cdrs where ( cdrstatuschangets < now() - 10 );
+---------------------+
| cdrstatuschangets |
+---------------------+
| 2009-09-25 13:55:50 |
+---------------------+
1 row in set (0.00 sec)
show warnings;
Empty set (0.00 sec)
IT技术经常有效,但有时候...
mysql>
select cdrstatuschangets from cdrs where ( cdrstatuschangets < now() - 50 );
+---------------------+
| cdrstatuschangets |
+---------------------+
| 2009-09-25 13:55:50 |
+---------------------+
1 row in set, 1 warning (0.00 sec)
show warnings;
+---------+------+-----------------------------------------------------------------------+
| Level | Code | Message | |
+---------+------+-----------------------------------------------------------------------+
| Warning | 1292 | Incorrect datetime value: '20090925211564.000000' for column 'cdrStatusChangeTS' at row 1 |
+---------+------+-----------------------------------------------------------------------+
1 row in set (0.00 sec)
有时候,尽管期望有结果,但选择结果并未出现。