UFN_APPUSER_HASPROXYUSER

            create function dbo.UFN_APPUSER_HASPROXYUSER(@ID uniqueidentifier)
            returns bit
            with execute as caller
            as begin

                if exists(select 1 from dbo.APPUSER where PROXYOWNERID = @ID)
                    begin
                        return cast(1 as bit);
                    end
                else
                    begin
                        return cast(0 as bit);
                    end
             return cast(1 as bit);
            end