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) 
OR (D.DEPT_CODE IS NOT NULL) 
ORDER BY O.DEPT_CODE ASC, O.ORDER_NO ASC;