问题 单项选择题

在关系数据库中,表是三级模式结构中的

A.外模式

B.模式

C.存储模式

D.内模式

答案

参考答案:B

解析:[命题目的] 本题考查关于数据库三级模式结构的知识点。
[解题要点] 数据库系统的三级模式指模式也称逻辑模式或者概念模式,对应的三级模式是视图。外模式也称子模式或者用户模式,对应的三级模式是关系数据库。内模式也称存储模式或者物理模式,对应的三级模式是基本表和存储文件。
[考点链接] 模式的概念、三级模式结构、二级映像与数据独立性。

不定项选择题
单项选择题

Who won the World Cup 1994 football game What happened at the United Nations How did the critics like the new play (1) an event takes place, newspapers are on the streets (2) the details. Wherever anything happens in the world, reporters are on the spot to (3) the news.

Newspapers have one basic (4) , to get the news as quickly as possible from its source, from those who make it to those who want to (5) it.

Radio, telegraph, television, and (6) inventions brought competition for newspaper. So did the development of magazines and other means of communication. (7) , this competition merely spurred the newspapers on. They quickly made use of the newer and faster means of communication to improve the (8) and thus the efficiency of their own operations. Today more newspapers are (9) and read than ever before. Competition also led newspapers to branch out into many other fields. Besides keeping readers (10) of the latest news, today’s newspapers (11) and influence readers about politics and other important and serious matters. Newspapers influence readers’ economic choices (12) advertising. Most newspapers depend on advertising for very (13) .

Newspapers are sold at a price that (14) even a small fraction of the cost of production. The main (15) of income for most newspapers is commercial advertising. The (16) in selling advertising depends on a newspaper’s value to advertisers. This (17) in terms of circulation. How many people read the newspaper

Circulation depends (18) on the work of the circulation department and on the services or entertainment (19) in a newspaper’s pages. But for the most part, circulation depends on a newspaper’s value to readers as a source of information (20) the community, city, county, state, nation, and world—and even outer space.

15()

A.source

B.origin

C.course

D.finance