如何使用注释指定列的组合应该是唯一约束? [英] How to specify that a combination of columns should be a unique constraint using annotations?

问题描述

我想确保表中的所有行都具有两个字段的唯一组合，并且我想在实体类中使用注释来指定这一点.我曾尝试使用 @Table 和 @UniqueConstraint 的组合，但显然我做错了，因为我似乎只能指定单独的列应该是唯一的(我已经可以指定使用 @Column 的唯一属性)而不是而不是列的组合.例如，我想要一个包含字段 A 和 B 的表只包含具有唯一 A 和 B 组合的行.两个字段/列都不需要是唯一的，两者的组合应该是唯一的.

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.

这是我迄今为止尝试过的，但没有任何乐趣:

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" }) })

有人可以建议正确的方法吗?此外，如果可以使用 JPA 注释而不是特定于 Hibernate 的注释，那会更好.

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.

预先感谢您的帮助.

--詹姆斯

推荐答案

第二次尝试

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

应该按预期工作.

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