此内容没有您所选择的语言版本。

14.8. Polymorphic queries


A query like:
from Cat as cat
Copy to Clipboard Toggle word wrap
returns instances not only of Cat, but also of subclasses like DomesticCat. Hibernate queries can name any Java class or interface in the from clause. The query will return instances of all persistent classes that extend that class or implement the interface. The following query would return all persistent objects:
from java.lang.Object o
Copy to Clipboard Toggle word wrap
The interface Named might be implemented by various persistent classes:
from Named n, Named m where n.name = m.name
Copy to Clipboard Toggle word wrap
These last two queries will require more than one SQL SELECT. This means that the order by clause does not correctly order the whole result set. It also means you cannot call these queries using Query.scroll().
返回顶部
Red Hat logoGithubredditYoutubeTwitter

学习

尝试、购买和销售

社区

关于红帽文档

通过我们的产品和服务,以及可以信赖的内容,帮助红帽用户创新并实现他们的目标。 了解我们当前的更新.

让开源更具包容性

红帽致力于替换我们的代码、文档和 Web 属性中存在问题的语言。欲了解更多详情,请参阅红帽博客.

關於紅帽

我们提供强化的解决方案,使企业能够更轻松地跨平台和环境(从核心数据中心到网络边缘)工作。

Theme

© 2025 Red Hat