ocp 11g試題解析：1Z0-051-042題，完整題庫請點(diǎn)擊這里聯(lián)系老師咨詢了解

42. Which three statements are true regarding views? (Choose three.)

A. Views can be created only from tables.

B. Views can be created from tables or other views.

C. Only simple views can use indexes existing on the underlying tables.

D. Both simple and complex views can use indexes existing on the underlying tables.

E. Complex views can be created only on multiple tables that exist in the same schema.

F. Complex views can be created on multiple tables that exist in the same or different schemas.

Answer: BDF

試題解析：

A錯(cuò)誤，視圖是一種基于表或其它視圖的邏輯表。

B正確，視圖是一種基于表或其它視圖的邏輯表。

C錯(cuò)誤，簡單視圖和復(fù)雜視圖都能使用相關(guān)表的索引。

D正確，同C.

E錯(cuò)誤，可以是不同schema間。

F正確，復(fù)雜視圖的子查詢可以是相同或者不同的schema間的多張表。