OCP-1Z0-051-V9.02-41题

41. Which two statements are true regarding views? (Choose two.)

A. A  subquery that defines a view cannot include the  GROUP BY clause.

B. A  view that is  created with the subquery having the DISTINCT keyword can be updated.   

C. A  view that is  created with the subquery having   the pseudo  column ROWNUM keyword cannot

be updated.

D. A  data manipulation language ( DML)  operation can be performed on a  view that is  created with

the subquery having all the NOT NULL columns of a table. 

Answer: CD

答案解析：

参考： http://blog.csdn.net/rlhua/article/details/12790467

A错误，创建视图的子查询可以使用group by子句。

B错误，子查询中带有DISTINCT 不能对视图进行DML操作。

C正确，子查询中带有 ROWNUM  关键字不能对视图进行DML操作。

D正确，所有非空列都可以进行DML操作。