UFN_EVENTSEATING_GETSEATAVAILABLE

            CREATE function dbo.UFN_EVENTSEATING_GETSEATAVAILABLE(@EVENTID uniqueidentifier)
            returns int
            with execute as caller
            as
            begin
                declare @AVAILABLE int;

                select
                    @AVAILABLE = count(SEAT.ID)
                from
                    dbo.EVENTSEATING as SEATING
                inner join dbo.EVENTSEATINGSECTION as SECTION on SECTION.EVENTSEATINGID = SEATING.ID
                inner join dbo.EVENTSEATINGSUBSECTION as SUBSECTION on SUBSECTION.EVENTSEATINGSECTIONID = SECTION.ID
                inner join dbo.EVENTSEATINGSEAT as SEAT on SUBSECTION.ID = SEAT.EVENTSEATINGSUBSECTIONID
                where
                    SEATING.ID = @EVENTID and
                    SEAT.REGISTRANTID is null

                return @AVAILABLE
            end