Does the constant HAVE to be stored in a table??
Would it not be easier to just have the UDF return the value? (it is constant after all)
as in:
CREATE FUNCTION fnGetConst(@cWanted INT)
RETURNS VARCHAR(5)
AS
BEGIN
DECLARE @RetValVARCHAR(5)
SELECT @RetVal = case @cWanted when 1 THEN 'boo'
when 2 THEN 'hoo' END
return @RetVal
END