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