SELECT (SELECT SUM(PRICE * ACCOUNT) FROM ORDERS, ORDERDETAIL WHERE ORDERDETAIL.ORDERID = ORDERS.ORDERID AND ORDERDATA BETWEEN '01-3月-97' AND '31-5月-97') AS 第2季销售额, (SELECT SUM(PRICE * ACCOUNT) FROM ORDERS, ORDERDETAIL WHERE ORDERDETAIL.ORDERID = ORDERS.ORDERID AND ORDERDATA BETWEEN '01-1月-97' AND '28-2月-97') AS 第1季销售额