java 使用JPA时如何映射没有主键的数据库视图
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How to map a database view without a primary key when using JPA
提问by Andy N
- I have views in a SQL database with no obvious primary key (composite or otherwise)
- I would like to access them through JPA
- 我在没有明显主键（复合或其他）的 SQL 数据库中有视图
- 我想通过 JPA 访问它们
I've read that I should be able to treat views in JPA like I treat tables (using the @Table annotation etc.). However without a primary key I have to effectively make a composite key out of EVERY COLUMN (in fact, this in what Hibernate's reverse-engineering tool seems to do by default).
我读过我应该能够像对待表格一样对待 JPA 中的视图（使用 @Table 注释等）。但是，如果没有主键，我必须有效地从每个列中创建一个复合键（实际上，这在 Hibernate 的逆向工程工具中似乎默认是这样做的）。
However if I do this there are undesirable side effects. E.g.
但是，如果我这样做会产生不良副作用。例如
Having to write all you code pointing to the primary key's attributes rather than the views:
myViewObject.getPrimaryKey().getFirstName()
Not being able to use the "findBy..." methods on the spring Repository (since that attribute is part of the view's "identifier" and not actually one of it's attributes).
必须编写指向主键属性而不是视图的所有代码：
myViewObject.getPrimaryKey().getFirstName()
无法在 spring 存储库上使用“findBy...”方法（因为该属性是视图“标识符”的一部分，实际上并不是它的属性之一）。
My question is: How do I map views in such a was as I can easily access their attributes using JPA?
我的问题是：如何在这样的情况下映射视图，因为我可以使用 JPA 轻松访问它们的属性？
Note: I'm quite happy to be told I'm using completely the wrong approach. This seems like such a common problem there's bound to be a better solution.
注意：我很高兴被告知我使用了完全错误的方法。这似乎是一个普遍存在的问题，肯定会有更好的解决方案。
回答by Vlad Mihalcea
You can add a UUID column to every row of the Views so then you can use the UUID column as an @Id.
您可以向视图的每一行添加一个 UUID 列，这样您就可以将 UUID 列用作 @Id。
