UFN_CONSTITUENT_ISVOLUNTEER

        create function dbo.UFN_CONSTITUENT_ISVOLUNTEER(@CONSTITUENTID uniqueidentifier) 
        returns bit
        with execute as caller
        as begin
            declare @CURRENTDATE datetime;
            set @CURRENTDATE = getdate();

            declare @UPPERBOUND datetime;
            set @UPPERBOUND = dbo.UFN_DATE_GETLATESTTIME(@CURRENTDATE);

            declare @LOWERBOUND datetime;
            set @LOWERBOUND = dbo.UFN_DATE_GETEARLIESTTIME(@CURRENTDATE);

            if exists(
                select
                    ID
                from
                    dbo.VOLUNTEERDATERANGE
                where
                    VOLUNTEERDATERANGE.CONSTITUENTID = @CONSTITUENTID and
                    (VOLUNTEERDATERANGE.DATEFROM <= @UPPERBOUND or VOLUNTEERDATERANGE.DATEFROM is null) and
                    (VOLUNTEERDATERANGE.DATETO >= @LOWERBOUND or VOLUNTEERDATERANGE.DATETO is null)
            ) return 1;

            return 0;
        end