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;