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How Views are Stored (175)

原创 网络安全 作者:tsinglee 时间:2007-11-10 15:28:15 0 删除 编辑

Unlike a table, a view is not allocated any storage space, nor does a view actually
contain data. Rather, a view is defined by a query that extracts or derives data from the
tables that the view references. These tables are called base tables. Base tables can in
turn be actual tables or can be views themselves (including materialized views).
Because a view is based on other objects, a view requires no storage other than storage
for the definition of the view (the stored query) in the data dictionary.

视图如何存储
1. 视图不占用任何存储空间 , 不包含实际的数据
2. 视图从他引用的基表中查询数据
3. 基表既可以是表,也可以是视图(包括物化视图)
4. 视图只在数据字典中保存了视图的定义

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