select
  d.DEPT_CODE
  , d.DEPT_NAME
  , o.ORDER_NO
  , c.CUST_CODE
  , c.CUST_NAME
  , o.ORDER_AMT
from
  TBL_ORDERS as o
inner join
  TBL_DEPT as d
on
  o.DEPT_CODE = d.DEPT_CODE
left join
  TBL_CUST as c
on
  o.CUST_CODE = c.CUST_CODE
order by
  d.DEPT_CODE
  , o.ORDER_NO
;