一、原题
View the Exhibit to examine the description for the SALES table.
Which views can have all DML operations performed on it? (Choose all that apply.)
A. CREATE VIEW v3
AS SELECT * FROM SALES
WHERE cust_id = 2034
WITH CHECK OPTION;
B. CREATE VIEW v1
AS SELECT * FROM SALES
WHERE time_id <= SYSDATE - 2*365
WITH CHECK OPTION;
C. CREATE VIEW v2
AS SELECT prod_id, cust_id, time_id FROM SALES
WHERE time_id <= SYSDATE - 2*365
WITH CHECK OPTION;
D. CREATE VIEW v4
AS SELECT prod_id, cust_id, SUM(quantity_sold) FROM SALES
WHERE time_id <= SYSDATE - 2*365
GROUP BY prod_id, cust_id
WITH CHECK OPTION;
答案 AB
二、题目翻译
下图是SALES表的描述。
可以在哪一个视图上面执行所有的DML操作？（选择所有正确的项）
三、题目解析
WITH CHECK OPTION选项：Oracle数据库禁止更改不包含在子查询条件里的行。
C不正确的是因为，视图只建了三列，而其它列不能为空，
D不正确的是因为聚合函数SUM(quantity_sold)需要一个别名，并且有聚合函数就是复杂视图，复杂视图是不能进行DML操作的。
