DELETE FROM ORDERS 
WHERE ORDER_DATE BETWEEN '2020-01-01' AND '2020-12-31';
DELETE FROM ORDERS_DTL
WHERE ORDERS_DTL.ORDER_NO IN (
  SELECT ORDERS_DTL.ORDER_NO
  FROM ORDERS_DTL
  LEFT OUTER JOIN ORDERS  ON ORDERS_DTL.ORDER_NO = ORDERS.ORDER_NO 
  WHERE ORDERS.ORDER_DATE BETWEEN '2020-01-01' AND '2020-12-31'
);