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