Question

I’m writing a stored procedure and I want to return 0 records when something fails. I can’t seem to figure out how to just return 0 rows? I’ve used SELECT NULL but this returns 1 row with a NULL in row 1 col 1. I have also tried not specifying any SELECT statements in my error code path but when testing the value of @@ROWCOUNT after the call to the SP, it returned 1. I think this may be because the @@ROWCOUNT was never reset from the SELECT statement earlier in the SP (in the EXISTS()). Any advice would be appreciated.

Also, I’ve got XACT_ABORT set to ON, but I have also used a TRY/CATCH block to ensure I return the correct error “return value” from the stored procedure. Is this okay? If there is an error, will the XACT_ABORT override the TRY/CATCH or will my error code path still lead to the correct return values being returned?

-- Setup
SET NOCOUNT ON; -- SET NOCOUNT ON added to prevent extra result sets from interfering with SELECT statements.
SET XACT_ABORT ON; -- SET XACT_ABORT ON rollback transactions on errors
DECLARE @return int; SET @return = 1; -- Default to general error

-- Start transaction
BEGIN TRANSACTION
    BEGIN TRY

        IF NOT EXISTS(SELECT NULL FROM [MyTable] WHERE [Check] = 1) 
        BEGIN

            -- Insert new record    
            INSERT INTO [MyTable] (Check, Date) VALUES (1, GETDATE());
            SELECT SCOPE_IDENTITY() AS [MyValue]; -- Return 1 row
            SET @return = 0; -- Success

        END
        ELSE
        BEGIN

            -- Fail
            SELECT NULL AS [MyValue]; -- Want to return 0 rows not 1 row with NULL
            SET @return = 2; -- Fail error

        END

    END TRY
    BEGIN CATCH

        -- Error
        ROLLBACK TRANSACTION;
        SELECT NULL AS [MyValue]; -- Want to return 0 rows not 1 row with NULL
        SET @return = 1; -- General error

    END CATCH

-- End transaction and return
COMMIT TRANSACTION
RETURN @return;

Answer 1

To return 0 rows, you can do:

SELECT TOP 0 NULL AS MyValue

Personally, I’d use an OUTPUT parameter for this sproc to return the ID back out instead of returning a resultset – that’s just my preference though. Then just set that output parameter to e.g. -1 as default to indicate nothing done.