【2019年8月版本】OCP 071认证考试最新版本的考试原题-第6题

choose three

Which three statements are true about indexes and their administration in an Orade database?

A) An INVISIBLE index is not maintained when Data Manipulation Language (DML) is performed on its underlying table.

B) An index can be created as part of a CREATE TABLE statement.

C) A DROP INDEX statement always prevents updates to the table during the drop opeaton

D) A UNIQUE and non-unique index can be ceated on the same table colunn

E) A descending index is a type of funcion-based index

F) If a query filters on an indexed column then it will always be used during execution of the query

Answer：BCE

(解析：建表的时候就能够建立索引;作 drop index 时会锁表;

建立降序排列的索引：

create index idx_emp_ename on emp(ename DESC) ;

建立了索引，在查询的时候不必定都会用到，涉及的因素不少。

)