SELECT
    d.DEPT_CODE,
    DEPT_NAME,
    ORDER_NO,
    c.CUST_CODE,
    CUST_NAME,
    ORDER_AMT
FROM
    TBL_ORDERS o
    INNER JOIN TBL_DEPT d
        ON o.DEPT_CODE = d.DEPT_CODE
    LEFT JOIN TBL_CUST c
        ON o.CUST_CODE = c.CUST_CODE
ORDER BY d.DEPT_CODE, ORDER_NO