SELECT D.DEPT_CODE, D.DEPT_NAME, O.ORDER_NO, C.CUST_CODE, C.CUST_NAME, O.ORDER_AMT 
FROM TBL_DEPT D, TBL_ORDERS O, TBL_CUST C 
WHERE D.DEPT_CODE = O.DEPT_CODE AND C.CUST_CODE = O.CUST_CODE 
AND D.DEPT_CODE IS NOT NULL OR C.CUST_CODE IS NULL 
ORDER BY O.DEPT_CODE ASC, O.ORDER_NO ASC;