OCP-1Z0-051-题目解析-第2题

2. 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;

Answer: AB

题目解析：

题目是问，哪个视图可以执行所有的DML操作，我们知道要在视图上执行insert操作，那么该视图就要包含基表所有的非空字段，所以可以明显的判断出来C和D是错误的，另外D选项的SUM(quantity_sold) 也是错误的，该字段必须要添加别名。