select code
     , name
     , cnt
     , ttl_amt
     , avg_amt
from (
    select
           c.CUST_CODE as CODE
         , c.CUST_NAME as NAME
         , count(*) as CNT
         , sum(o.ORDER_AMNT) as TTL_AMT
         , round(avg(o.ORDER_AMNT)) as AVG_AMT
    from CUSTOMER c left outer join ORDERS o
      on c.CUST_CODE = o.CUST_CODE
    where o.ORDER_DATE between '2023-09-01' and '2023-09-30'
    group by c.CUST_CODE
)
where cnt >= 5
order by CNT desc, AVG_AMT desc, CODE asc
;