我们如何忽略MySQL DATEDIFF()函数返回的负值？
众所周知，该DATEDIFF()函数用于获取两个日期之间的天数差。因此，很有可能返回负值。
mysql> select * from differ; +------------+-------------+ | OrderDate | WorkingDate | +------------+-------------+ | 2017-10-22 | 2017-10-29 | | 2017-10-25 | 2017-10-30 | | 2017-10-25 | 2017-11-30 | +------------+-------------+ 3 rows in set (0.00 sec)
上面的查询将返回表“differ”中的值。现在，如果有人想获得OrderDate和WorkingDate之间的差异，则输出将为负，如下所示：
mysql> Select DATEDIFF(OrderDate, WorkingDate)AS 'DIFFERENCE IN DAYS' from differ; +--------------------+ | DIFFERENCE IN DAYS | +--------------------+ | -7 | | -5 | | -36 | +--------------------+ 3 rows in set (0.00 sec)
但是我们可以使用MySQLABS()函数忽略这些负值，可以按以下步骤进行操作-
mysql> Select ABS(DATEDIFF(OrderDate, WorkingDate))AS 'DIFFERENCE IN DAYS' from differ; +--------------------+ | DIFFERENCE IN DAYS | +--------------------+ | 7 | | 5 | | 36 | +--------------------+ 3 rows in set (0.00 sec)