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 having count(productid)>1 group by productid

D、select productid from orders group by productid having count(productid)>1

请帮忙给出正确答案和分析，谢谢！