Once again, this feature involves only Hibernate and the database, and thus doesn't alter the class hierarchy.

再次声明，这些特性只包含Hibernate和数据库，所以不会改变类的层次结构。

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These tools can be used to select specific attributes from a database or create a new feature class that consists of a smaller area.

这些工具可用于从数据库中选取特定属性或创建一个由较小区域构成的新的元素类，。

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