现有订单表orders,包含用户信息userid,产品信息productid,以下()语句能够返回至少被订购过两次的productid?
A.
SELECT productid FROM orders WHERE count(productid)>1
B.
SELECT productid FROM orders WHERE max(productid)>1
C.
SELECT productid FROM orders WHERE havingcount(productid)>1 group by productid
D.
SELECT productid FROM orders group by productid having count(productid)>1