SELECT
    T_D.DEPT_CODE, DEPT_NAME, ORDER_NO, T_C.CUST_CODE, CUST_NAME, ORDER_AMT
FROM
    TBL_ORDERS AS T_O
INNER JOIN TBL_DEPT AS T_D
    ON T_D.DEPT_CODE = T_O.DEPT_CODE
LEFT OUTER JOIN TBL_CUST AS T_C
    ON T_C.CUST_CODE = T_O.CUST_CODE
ORDER BY
    T_O.DEPT_CODE ASC
   ,T_O.ORDER_NO DESC