As you learned earlier in the book, this form of inheritance is supported through the use of a discriminator column in your database as well as the UI, as seen in Figure 12-2.

在图12 - 2，在之前本书中学习到的这个界面支持在你的数据库使用列识别器来设计继承。

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Because Hibernate doesn't know what specific class you're after, it has to read every column (including the discriminator column), then determine which class to instantiate and, finally, populate it.

因为Hibernate不知道您要查询哪个特定的类，所以必须读取每个列(包括discriminator类)，然后才能决定要初始化哪个类，最后再填充它。

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