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