select 
b.DEPT_CODE,
b.DEPT_NAME,
a.ORDER_NO,
c.CUST_CODE,
c.CUST_NAME,
a.ORDER_AMT
from TBL_ORDERS as A
inner join TBL_DEPT as b
on a.DEPT_CODE = b.DEPT_CODE
left outer join TBL_CUST as c
on a.CUST_CODE = c.CUST_CODE