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