关系数据库是表的集合。对视图进行查询，本质上就是查询从（ ）中获得的数据。
- A.一个视图
- B.一个或若干个索引文件
- C.一个或若干个视图
- D.一个或若干个基本表
正确答案及解析
正确答案
解析
在关系数据库中，基本表存放的是各种信息。
索引文件由数据文件组成，它是带索引的顺序文件。
视图是从一个或多个表或视图中导出的表；其结构和数据是建立在对表的查询基础上；视图不是真实存在的基础表，而是一个虚拟表；数据库中只存放视图的定义；视图的数据是没有实际存放，视图的数据结构存储在数据库中。
从本质上来看对视图进行查询，就是从一个或若干个基本表中进行数据查询。
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