SELECT
    DP.DEPT_CODE,
    DP.DEPT_NAME,
    OD.ORDER_NO,
    CS.CUST_CODE,
    CS.CUST_NAME,
    OD.ORDER_AMT
FROM
    TBL_ORDERS AS OD
    INNER JOIN TBL_DEPT AS DP 
        ON DP.DEPT_CODE = OD.DEPT_CODE
    LEFT OUTER JOIN TBL_CUST AS CS
        ON CS.CUST_CODE = OD.CUST_CODE 
ORDER BY
    OD.DEPT_CODE ASC,
    OD.ORDER_NO ASC;