delete from
    ORDERS_DTL AS OD
where
    OD.ORDER_NO IN (
        SELECT
            OH.ORDER_NO
        FROM
            ORDERS AS OH
        WHERE
            OH.ORDER_DATE >= '2010-01-01'
            AND OH.ORDER_DATE <= '2010-12-31'
            );

DELETE FROM
    ORDERS
WHERE
    ORDER_DATE >= '2010-01-01'
    AND ORDER_DATE <= '2010-12-31';