mysql - MySQL 中 DATE_ADD/INTERVAL 的反转

Question

在mysql中，我们可以做如下添加月份:

SELECT DATE_ADD('2014-08-20', INTERVAL 13 MONTH); //Result: 2015-09-20

有什么办法可以进行反向操作吗？示例:

SELECT DIFF_IN_MONTHS('2015-09-20', '2014-08-20') //Result: 13

由于日差造成的四舍五入对我来说不是问题。

Answer 1

函数TIMESTAMPDIFF这样做:

SELECT TIMESTAMPDIFF(MONTH, '2015-09-20', '2014-08-20');

TIMESTAMPDIFF(unit,datetime_expr1,datetime_expr2)

Returns datetime_expr2 – datetime_expr1, where datetime_expr1 and datetime_expr2 are date or datetime expressions. One expression may be a date and the other a datetime; a date value is treated as a datetime having the time part '00:00:00' where necessary. The unit for the result (an integer) is given by the unit argument