select
    c.CUST_CODE as CODE
    , CUST_NAME as NAME
    , count(distinct ORDER_DATE) as CNT
from 
    CUSTOMER c
    left outer join(
        select 
            ORDER_NO
            , ORDER_DATE
            , CUST_CODE
        from ORDERS
        where
            ORDER_DATE between '2023-07-01' and '2023-07-31'
    ) o
        on c.CUST_CODE = o.CUST_CODE
group by
    c.CUST_CODE
    , CUST_NAME
order by 
    CNT desc
    , CODE desc
;