select
    tor.dept_code as DEPT_CODE
    ,td.dept_name as DEPT_NAME
from tbl_orders as tor
left outer join tbl_dept as td
on tor.dept_code = td.dept_code
union
select
    ts.dept_code as DEPT_CODE
    ,td.dept_name as DEPT_NAME
from tbl_sales  as ts
left outer join tbl_dept as td
on ts.dept_code = td.dept_code
order by DEPT_CODE