SELECT C.CUST_CODE CODE, C.CUST_NAME NAME, COUNT(O.CUST_CODE) CNT
    FROM
        -- ORDER_DATEが同じ場合は1件として扱う
        (SELECT CUST_CODE,ORDER_DATE FROM ORDERS GROUP BY CUST_CODE, ORDER_DATE) O
        INNER JOIN CUSTOMER C ON O.CUST_CODE = C.CUST_CODE
    WHERE O.ORDER_DATE BETWEEN '2023-07-01' AND '2023-07-31'
    GROUP BY O.CUST_CODE
    ORDER BY
        CNT DESC,
        CODE DESC