DELETE
FROM ORDERS_DTL
WHERE EXISTS (
    SELECT 1
    FROM ORDERS
    WHERE ORDERS.ORDER_DATE BETWEEN '2010-01-01' AND '2010-12-31'
    AND ORDERS.ORDER_NO = ORDERS_DTL.ORDER_NO
)
;
DELETE
FROM ORDERS
WHERE ORDERS.ORDER_DATE BETWEEN '2010-01-01' AND '2010-12-31'
;