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 b.DEPT_CODE = a.DEPT_CODE

LEFT OUTER JOIN TBL_CUST as c on c.CUST_CODE =a.CUST_CODE

ORDER BY a.DEPT_CODE asc, a.ORDER_NO;