OCP-1Z0-新051-61题版本-48

QUESTION NO: 48

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

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

B. A view is created with the sub query having the DISTINCT keyword can be updated

C. A Data Manipulation Language (DML) operation can be performed on a view that is created

with the sub query having all the NOT NULL columns of a table

D. A view that is created with the sub query having the pseudo column ROWNUM keyword cannot be updated

Answer: C,D

答案解析：

参考：41：http://blog.youkuaiyun.com/rlhua/article/details/12793479

Explanation:

Rules for Performing DML Operations on a View

You cannot add data through a view if the view includes:

Group functions

A GROUP BY clause

The DISTINCT keyword

The pseudocolumn ROWNUM keyword

Columns defined by expressions

NOT NULL columns in the base tables that are not selected by the view