我想在SQL里建一个视图,有三张表 ,需要从这三张表里取数据答:SELECT --quantity,discountprice,abbrev, --这三个不需要么? customer_id,checkdate,SUM(xiaoshoue)FROM ( SELECT A.checkid,customer_id,checkdate, quantity,discountprice, abbrev, quantity*discountprice AS xiaoshoue FROM CHECK A FULL JOIN CHECKGOODS ON A...