如何解决SQL Server中日期时间转换错误

Question

下面是我的代码:

DECLARE @dayscount int
SET @dayscount = CAST(DATEDIFF(day, CONVERT(VARCHAR(20), '21/02/2021', 103), CONVERT(VARCHAR(20), '22/02/2021',103)) AS int)
SELECT @dayscount

我得到这个错误:

Msg 241, Level 16, State 1, Line 2
从字符串

转换日期和/或时间失败

Answer 1

如果使用CONVERT函数，数据类型应该是date类型而不是varchar类型。

select CAST(DATEDIFF(day, CONVERT(date, '21/02/2021', 103), CONVERT(date, '22/02/2021',103)) AS int)