UFN_SITEID_MAPFROM_MEMBERSHIPID

create function [BBDW].[UFN_SITEID_MAPFROM_MEMBERSHIPID]
  (  
    @MEMBERSHIPID uniqueidentifier  
  )   
  returns uniqueidentifier
    as  

    begin
      declare @ID uniqueidentifier;
      select @ID = case when mp.[SITESYSTEMID] <> '00000000-0000-0000-0000-000000000000' then mp.[SITESYSTEMID] else null end 
      from BBDW.[DIM_MEMBERSHIPPROGRAM] mp 
      left join BBDW.[DIM_MEMBERSHIP] m on mp.[MEMBERSHIPPROGRAMDIMID] = m.[MEMBERSHIPPROGRAMDIMID]
      where m.[MEMBERSHIPSYSTEMID] = @MEMBERSHIPID;
      return @ID
    end