SELECT *
FROM (
     SELECT DISTINCT C.CUSID||': '||C.CUS_NAME AS Customer,
       RANK()
           OVER (
               ORDER BY COUNT(DISTINCT O.ORDER#) DESC
               ) AS RANK1,
       RANK()
           OVER (
               ORDER BY SUM(OD.QUOTED_PRICE*OD.NUM_ORDERED)/COUNT(DISTINCT OD.ORDER#) DESC
               ) AS RANK2
FROM CUSTOMER C
    JOIN T_ORDERS O ON C.CUSID = O.CUSID
    JOIN ORDER_DETAILS OD ON O.ORDER# = OD.ORDER#
    GROUP BY C.CUSID||': '||C.CUS_NAME
         )
WHERE RANK1 <= 2 OR RANK2 <=2;