select distinct TBL_ORDERS.DEPT_CODE, TBL_DEPT.DEPT_NAME
from TBL_ORDERS
left join TBL_DEPT
on TBL_ORDERS.DEPT_CODE = TBL_DEPT.DEPT_CODE
union
select distinct TBL_SALES.DEPT_CODE, TBL_DEPT.DEPT_NAME
from TBL_SALES
left join TBL_DEPT
on TBL_SALES.DEPT_CODE = TBL_DEPT.DEPT_CODE 
order by 1 asc ;