select
 T1.dept_code
 , T1.dept_name
 , T2.order_no
 , T3.cust_code
 , T3.cust_name
 , T2.order_amt
from tbl_dept T1
inner join tbl_orders T2 on
  T1.dept_code = T2.dept_code
left outer join tbl_cust T3 on
  T2.cust_code = T3.cust_code
order by 
  T1.dept_code asc
  , T2.order_no asc;