Stored Procedure NULL Parameter

Question

I have a database table I am trying to do an UPDATE/INSERT to with a stored procedure. Let's define the table like so:

CREATE TABLE Foo
(
    Id           INT             IDENTITY(1, 1),
    Name         VARCHAR(256)    NOT NULL,
    ShortName    VARCHAR(32),
    Sort         INT
);

I have written a stored procedure similar to the following:

CREATE PROCEDURE Put_Foo
(
    @Id           INT             = NULL OUTPUT,
    @Name         VARCHAR(256),
    @ShortName    VARCHAR(32)     = NULL,
    @Sort         INT             = NULL
)
AS
BEGIN
    SET NOCOUNT ON;

    SELECT
        @Id = F.Id
    FROM
        Foo AS F
    WHERE
        F.Name = @Name;

    IF (@Id IS NOT NULL)
    BEGIN
        UPDATE
            Foo
        SET
            ShortName    = @ShortName,
            Sort         = @Sort
        WHERE
            Id = @Id;
    END
    ELSE
    BEGIN
        INSERT
        INTO Foo
        (
            Name,
            ShortName,
            Sort
        )
        VALUES
        (
            @Name,
            @ShortName
            @Sort
        );

        SET @Id = SCOPE_IDENTITY();
    END

    RETURN;
END;

I've greatly simplified the data structures I am dealing with but I hope this serves my point. My question is in regards to how the parameters are processed. Is there a way to determine within the procedure if @Sort was passed in as NULL or set NULL by the default declaration in the parameter list?

EDIT:

The purpose of this is that I don't want NULL parameters to override any columns in the UPDATE statement unless they are explicitly passed in that way.

Answer 1

No, you can't detect how @Sort became NULL. If your goal is to capture when it is explicitly set versus it being set by the default, I would suggest using a different default value (maybe one that wouldn't normally be used, like -1). Then you can assume that if @Sort is NULL, it was explicitly passed in, but if it is -1, you know it was set by default.