40.View the Exhibit to examine the description for the SALES and PRODUCTS tables.

40.View the Exhibit to examine the description for the SALES and PRODUCTS tables.

You want to create a SALE_PROD view by executing the following SQL statement:

CREATE VIEW sale_prod

AS SELECT p.prod_id, cust_id, SUM(quantity_sold) "Quantity" , SUM(prod_list_price) "Price"

FROM products p, sales s

WHERE p.prod_id=s.prod_id

GROUP BY p.prod_id, cust_id;

Which statement is true regarding the execution of the above statement?

A.The view will be created and you can perform DML operations on the view.

B.The view will be created but no DML operations will be allowed on the view.

C.The view will not be created because the join statements are not allowed for creating a view.

D.The view will not be created because the GROUP BY clause is not allowed for creating a view.



答案：B

解析：

视图有两种

1.简单视图:包含一个子查询，只从一个基表中检索数据

2.复杂视图:包含一个子查询，从多个基表中检索数据，使用group by或distince子句对行分组，包含函数的调用,或者伪列

只能对简单视图执行dml操作

A：错误，该视图是复杂视图，不能进行dml操作

B：正确

C：错误，复杂视图可以包括多表的链接

D：错误，复杂视图可以包括group by