如何檢查日期是否存在的條件

Question

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

轉換日期和/或時間字符串即將到來時轉換失敗。

如何檢查上述問題的條件......

Answer 1

使用ISDATE()函數來檢查是否字符串是一個有效的日期

Answer 2

使用查詢：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

使用日期時間..同樣爲第9個月第31日

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