针对数据库bookshop，若要给所有姓“刘”的客户的订单金额增加10%，以下操作正确的是（ ）。
选项：

A:update salesset total_amt=total_amt*1.1where cust_name in(select cust_name from customer where cust_name like '刘%');
B:update salesset total_amt=total_amt*1.1where cust_name=(select cust_name from customer where cust_name like '刘%');
C:update salesset total_amt=total_amt*1.1from customer,saleswhere sales.cust_name=customer.cust_name and customer.cust_name like '刘%';
D:update salesset total_amt=total_amt*1.1where exists (select * from customer where sales.cust_name=customer.cust_name and customer.cust_name like '刘%')