如何在SQL Server 2008中将where子句与datetime一起使用

Question

I have written this query:

SELECT * 
FROM w_tbl 
WHERE DID NOT IN (SELECT DId FROM tbl_Assign) 
  AND CAST(MeasDateTime AS Date) = @dta 
ORDER BY 
    CAST(MeasDateTime as DATE) DESC

So as you can see I am sending a parametrized query.

So I put 24/09/2010 00:00:00 for @dta

But I get this error:

Conversion failed when converting date and/or time from charterer string.

I tell you why I am doing this and my purpose:

I have a datetime column, and I want to select/fetch all data by date only (ie I don't want to fetch datetime wise, it has to be just according to date)

Answer 1

If you want to select by date only and you have DateTime type, use date functions:

DATEADD ( dd , 0 , DATEDIFF ( dd , 0 , @dta))

So in your case:

SELECT * 
FROM w_tbl 
WHERE DID NOT IN (SELECT DId FROM tbl_Assign) 
  AND DATEADD ( dd , 0 , DATEDIFF ( dd , 0 , MeasDateTime)) = DATEADD ( dd , 0 , DATEDIFF ( dd , 0 , @dta)) 
ORDER BY 
    MeasDateTime DESC -- No need for CAST/CONVERT here, it will be ok either way

Answer 2

First check @dta value cause 24/09/2010 may be wrong date. Try using 09/24/2010 or 24-Sep-2010 and check. Always to avoid confusion in dd/MM/yyyy and MM/dd/yyyy use MMM for month. SQL handles datetime format with MMM correctly. Like dd-MMM-yyyy. By default SQL uses US standards and take date is format MM/dd/yyyy.

Thanks.