SELECT
    OD.DEPT_CODE,
    DP.DEPT_NAME,
    OD.ORDER_NO,
    OD.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;