在bookshop数据库中有5 个表,这五个表的结构描述见“实验数据库描述”。其中员工表employee(emp_no,emp_name,sex,dept,title,date_hired,birthday,salary,telephone,addr),客户表customer(cust_name,receiver,tel_no,cust_Addr),图书表books(book_no,book_name,price,book_type,ISBN),销售主表sales(order_no,cust_name,sale_id,total_amt,order_date),销售明细表sale_item(order_no,book_no,qty,unit_price)。针对数据库bookshop,若要给所有姓“”的客户的订单金额增加10%,以下操作正确的是( )。
A.
update sales set total_amt=total_amt*1.1 where cust_name in (select cust_name from customer where cust_name like '%')
B.
update sales set total_amt=total_amt*1.1 where cust_name = (select cust_name from customer where cust_name like '%')
C.
update sales set total_amt=total_amt*1.1 from customer,sales where sales.cust_name=customer.cust_name and customer.cust_name like '%'
D.
update sales set total_amt=total_amt*1.1 where exists (select * from customer where sales.cust_name=customer.cust_name and customer.cust_name like '%')