select
DP.DEPT_CODE,
DP.DEPT_NAME,
OD.ORDER_NO,
CS.CUST_CODE,
CS.CUST_NAME,
OD.ORDER_AMT
from TBL_ORDERS as OD
    inner join TBL_DEPT as DP
    on DP.DEPT_CODE = OD.DEPT_CODE
    
    left outer join TBL_CUST as CS
    on CS.CUST_CODE = OD.CUST_CODE
    
order by OD.DEPT_CODE, OD.ORDER_NO