如何指定列的组合应该是使用注解的唯一约束？

问题描述

我想确保我的表中的所有行有两个领域的独特组合，我想在我的实体类指定这个使用注释。我一直在使用@Table和@UniqueConstraint但组合尝试显然我做错了，因为我只能似乎来指定单独的列应该是唯一的（我已经可以指定使用@列的唯一属性），而比列的组合。例如，我想其中有场A和B只包含具有A和B都不领域的一个独特的组合行的表/列的需要是唯一的，这是两者的结合应该是独一无二的。

I want to make sure that all rows in my table have a unique combination of two fields, and I want to specify this using annotations in my entity class. I have tried using a combination of @Table and @UniqueConstraint but apparently I'm doing it wrong, in that I can only seem to specify that the separate columns should be unique (I can already specify that using the @Column's unique property) rather than a combination of columns. For example I want a table which has fields A and B to contain only rows which have a unique combination of A and B. Neither field/column needs to be unique, it's the combination of the two which should be unique.

下面就是我没有快乐到目前为止已经试过：

Here's what I've tried so far with no joy:

@Table(name = "MY_TABLE", 
       uniqueConstraints = @UniqueConstraint(columnNames = 
                                             { "FIELD_A", "FIELD_B" }))

和

@Table(name = "MY_TABLE", 
       uniqueConstraints = { @UniqueConstraint(columnNames = 
                                               { "FIELD_A", "FIELD_B" }) })

有人可以请建议这样做的正确方法？此外，如果有可能使用JPA注释，而不是Hibernate的相关注解会是preferable。

Can someone please suggest the right way to do this? Also if it's possible to use JPA annotations instead of Hibernate-specific annotations that'd be preferable.

在此先感谢您的帮助。

- 詹姆斯

推荐答案

你的第二个尝试

@Table(name = "MY_TABLE", 
   uniqueConstraints = { @UniqueConstraint(columnNames = 
                                           { "FIELD_A", "FIELD_B" }) })

应该工作正常。

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