Atualizar oldID para os registros recursivamente

 Update #customer
 SET oldid =
        (Select TOP 1 c_old.id from #customer c_old
          where c_old.enddate <= #customer.startdate
          and c_old.cust_no = #customer.cust_no
          and c_old.meter_no = #customer.meter_no
          and c_old.enddate = 
                           (
                             SELECT max(c.enddate) FROM #customer c
                               where c_old.cust_no = c.cust_no
                               and c_old.meter_no = c.meter_no
                               and #customer.startdate >= c.enddate
                            ) 
          )
  from #customer
 go