UFN_REGISTRANTRESTRICTIONOPTION_ISUNIQUE

            create function dbo.UFN_REGISTRANTRESTRICTIONOPTION_ISUNIQUE
            (
                @REGISTRANTID uniqueidentifier,
                @EVENTRESTRICTIONOPTIONID uniqueidentifier
            )
            returns bit
            as begin

                declare @ISUNIQUE bit = 0;
                declare @OPTIONCOUNT integer = 0;

                select 
                    @OPTIONCOUNT = count(ID)  
                from 
                    dbo.REGISTRANTRESTRICTIONOPTION 
                where 
                    REGISTRANTID = @REGISTRANTID 
                    and
                    EVENTRESTRICTIONOPTIONID = @EVENTRESTRICTIONOPTIONID

                if @OPTIONCOUNT <= 1
                    set @ISUNIQUE = 1;

                return @ISUNIQUE
            end