Question

This is my statement

IF (@UserName IS NULL AND @EditorKey IS NULL) OR (@UserName IS NOT NULL AND @EditorKey IS NOT NULL) BEGIN
    RAISERROR ('One of @UserName, @EditorKey must be non-null.', 15, 0)
    RETURN
END

What I want is to be able to do something like this:

IF (@UserName IS NOT NULL) XOR (@EditorKey IS NOT NULL) BEGIN
    RAISERROR ('One of @UserName, @EditorKey must be non-null.', 15, 0)
    RETURN
END

For two parameters it isn’t that big of a deal, but some procs have three or four where in only one may be passed and the rest should be null.

Answer 1

Not very succinct, but you could expand out the logic like this:

WHERE
    (NOT ((@UserName IS NOT NULL) AND (@EditorKey IS NOT NULL))) AND
    ((@UserName IS NOT NULL) OR (@EditorKey IS NOT NULL))

Or use the bitwise XOR operator (^):

WHERE
    (CASE WHEN (@UserName IS NOT NULL) THEN 1 ELSE 0 END) ^
    (CASE WHEN (@EditorKey IS NOT NULL) THEN 1 ELSE 0 END) = 1

You can use a similar approach where there are three or four parameters, and exactly one must have a value:

WHERE
    (CASE WHEN (@Var1 IS NOT NULL) THEN 1 ELSE 0 END) +
    (CASE WHEN (@Var2 IS NOT NULL) THEN 1 ELSE 0 END) +
    (CASE WHEN (@Var3 IS NOT NULL) THEN 1 ELSE 0 END) +
    (CASE WHEN (@Var4 IS NOT NULL) THEN 1 ELSE 0 END) = 1