DELETE 
FROM
    ORDERS_DTL 
WHERE
    ORDER_NO IN ( 
        SELECT
            ORDER_NO 
        FROM
            ORDERS 
        WHERE
            ORDER_DATE BETWEEN '2010-01-01' AND '2010-12-31'
    ); 
DELETE 
FROM
    ORDERS 
WHERE
    ORDER_DATE BETWEEN '2010-01-01' AND '2010-12-31';