SELECT tdep.DEPT_CODE
    ,tdep.DEPT_NAME
    ,tord.ORDER_NO
    ,tcus.CUST_CODE
    ,tcus.CUST_NAME
    ,tord.ORDER_AMT
FROM TBL_ORDERS AS tord
JOIN TBL_DEPT AS tdep
ON tord.DEPT_CODE = tdep.DEPT_CODE

LEFT OUTER JOIN TBL_CUST AS tcus
ON tord.CUST_CODE = tcus.CUST_CODE
ORDER BY tord.DEPT_CODE
    ,tord.ORDER_NO ASC;