SQL Server output parameter issue

Question

I am using SQL Server 2008 Enterprise. I am learning OUTPUT parameter of SQL Server stored procedure. For example, stored procedure sp_add_jobschedule has an OUTPUT paramete

Answer 1

Two other things I think that are worth noting:

1) You can pass more than one parameter as OUTPUT,

2) You do not have to call the parameters with OUTPUT if you don't want the results

CREATE PROCEDURE ManyOutputs @a int, @b int output, @c varchar(100) output, @d bit output
AS
BEGIN
    SET @b = @a + 11
    SET @c = 'The Value of A is ' + CAST(@a AS varchar(5)) + ', and the value of B is ' + CAST(@b AS varchar(5))
    IF (@a % 2 = 1)
        SET @d = 1
    ELSE
        SET @d = 0
END
GO

Calling this routine:

DECLARE @bVal int
DECLARE @cVal varchar(100)
DECLARE @dVal bit

EXEC ManyOutputs 1, @bVal, @cVal, @dVal
SELECT @bVal AS bVal, @cVal as cVal, @dVal as dVal

Returns NULL, NULL, NULL

EXEC ManyOutputs 2, @bVal OUT, @cVal OUT, @dVal OUT
SELECT @bVal AS bVal, @cVal as cVal, @dVal as dVal

Returns 13, "The Value of A is 2, and the value of B is 13", 0

EXEC ManyOutputs 3, @bVal, @cVal, @dVal
SELECT @bVal AS bVal, @cVal as cVal, @dVal as dVal

Returns 13, "The Value of A is 2, and the value of B is 13", 0

(the same as the last call, because we didn't get new values by using OUTPUT, so it retained the old values.)

EXEC ManyOutputs 5, @bVal OUT, @cVal OUT, @dVal OUT
SELECT @bVal AS bVal, @cVal as cVal, @dVal as dVal

Returns 16, "The Value of A is 5, and the value of B is 16", 1

Answer 2

Adding further to what others have said above, OUTPUT parameters can act as INPUT as well as OUTPUT. But, it depends on the stored procedure to use the value passed to it.

If the stored procedures ignores the value passed in for OUTPUT parameter (which it generally should), the INPUT value gets ignored anyway.

Using Sergey's code, I can use the value user passed for @intOutput (if I need to)

create PROCEDURE test_proc

@intInput int,
@intOutput int OUTPUT

AS
set @intOutput = @intOutput + 1 

go

But, that defeats the purpose of OUTPUT parameter.
To give a different view, c# compiler forces you to overwrite the out parameter's value by assignment (without using the output parameter).

e.g. I cannot do this in c#. Here it acts as only out parameter (i.e ignore the value user passed to this function)

static void dosomething(out int i)
{
    //i = 0;
    i = i + 1;
}