不同月份之间的日期差异

Question

有没有一种方法可以按月进行datediff以便正确显示总数？与我进行整个范围测试相比，以下是两个简短的说明。如果我给每个加+1，则总数为62。谢谢。

SELECT DATEDIFF(day, '2019/07/13', '2019/07/31') AS DateDiff = 18
SELECT DATEDIFF(day, '2019/08/01', '2019/08/31') AS DateDiff = 30
SELECT DATEDIFF(day, '2019/09/01', '2019/09/12') AS DateDiff = 11
                                                             = 59

SELECT DATEDIFF(day, '2019/07/13', '2019/09/12') AS DateDiff = 61