SELECT
    D.dept_code
    , D.dept_name
    , O.order_no
    , C.cust_code
    , C.cust_name
    , O.order_amt 
FROM
    tbl_orders O 
    INNER JOIN tbl_dept D 
        ON O.dept_code = D.dept_code 
    LEFT OUTER JOIN tbl_cust C 
        ON O.cust_code = C.cust_code 
ORDER BY
    D.dept_code ASC
    , O.order_no ASC