在SQL中，建立视图用的命令是（）。

A:CREATE SCHEMA B:CREATE TABLE C:CREATE VIEW D:CREATE INDEX

One of the difficulties in building an SQL-like query language for the Web is the absence of a database (131) for this huge, heterogeneous repository of information. However, if we are interested in HTML documents only, we can construct a virtual schema from the implicit structure of these files. Thus, at the highest level of (132) , every such document is identified by its Uniform Resource Locator (URL), and a (133) and a text. Also, Web severs provide some additional information such as the type, length, and the last modification date of a document. So for data mining purposes, we can consider the set of all HTML documents as a relation:
Document (url, rifle, text, type, length, modif)
Where all the (134) are character strings. In this framework, an individual document is identified with a (135) in this relation. Of course, if some optional information is missing from the HTML document, the associate fields will be left blank, but this is not uncommon in any database.

A:schema B:platform C:module D:relation

下面是SQL主要数据定义语句列表，其中哪一(些)行是正确的( ) 操作对象 操作方式 创 建 删 除 修 改 模式 CREATE SCHEMA DROP SCHEMA ALTER SCHEMA 基本表 CREATE 1IABLE DROP TABLE ALTER TABLE 视图 CREATEVIEW DROP VIEW ALTER VIEW 索引 CREATE INDEX DROP INDEX ALTER INDEX 域 CREATE DOMAIN DROP DOMAIN ALTER DOMAIN

A:仅“模式”行 B:仅“基本表”行 C:仅“视图”行和“索引”行 D:所有行

在SQL中，创建基本表用________。

A:CREATE SCHEMA命令 B:CREATE TABLE命令 C:CREATE INDEX命令 D:CREATE VIEW命令

在标准SQL中，建立视图的命令是______。

A:CREATE SCHEMA命令 B:CREATE TABLE命令 C:CREATE VIEW命令 D:CREATE INDEX命令

在标准SQL中，建立视图的命令是______。

A:CREATE SCHEMA 命令 B:CREATE TABLE 命令 C:CREATE VIEW 命令 D:CREATE INDEX 命令

在标准SQL中，建立视图的命令是______。

A:CREATE SCHEMA命令 B:CREATE TABLE命令 C:CREATE VIEW命令 D:CREATE INDEX命令