如何检查条件是否存在日期

Question

select CAST((CAST(2014 AS VARCHAR) + '-' + CAST(9 AS VARCHAR) + '-' + CAST(31 AS VARCHAR)) AS DATE)

从字符串转换日期和/或时间时转换失败。

如何检查上述问题的条件......

Answer 1

使用ISDATE()函数检查字符串是否为有效日期

Answer 2

使用查询：使用ISDate（）

IF ISDATE((CAST(2014 AS VARCHAR) + '-' + CAST(9 AS VARCHAR) + '-' 
    + CAST(31 AS VARCHAR))) = 1
   SELECT CAST(CAST(2014 AS VARCHAR) + '-' + CAST(9 AS VARCHAR) + '-' + 
       CAST(31 AS VARCHAR) AS DATETIME)
ELSE
    SELECT NULL

Answer 3

使用DateTime ..也是第9个月没有第31个

IF ISDATE(CAST((CAST(2014 AS VARCHAR) + '-' + CAST(9 AS VARCHAR) + '-' + CAST(30 AS VARCHAR)) AS DATETIME)) = 1
    PRINT 'VALID'
ELSE
    PRINT 'INVALID';