OCP-1Z0-051-題目解析-第41題

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 


A：子查詢定義視圖不能使用group by 子句（錯誤，有group by 子句的視圖是複雜視圖）
B：帶有Distinct關鍵字的視圖能被更新（錯誤，Distinct是去重複後的數據）
C：子查詢中包含僞列rownum的視圖不能被更新（正確）
D：通過子查詢建立的視圖，含有基表所有的非空列，可以執行DML操作 （正確）