SQL JPA-多列作为主键
问题描述：
如果我想让严重列组成ID.
If i want severeal Column to make up an ID.
SQL示例:
CONSTRAINT [PK_NAME] PRIMARY KEY ([Column1],[Column2],[Column3])
如何使用Jpa Entity类来做到这一点?通过columndefinition吗?
How can i do that with a Jpa Entity class ? through columndefinition ?
只需将id字段设置为:
just setting the id field as:
value = Column1 + Column2 + Column3 // aint working.
答
您需要为复合键提供一个类:
You need to have a class for your composite key:
public class CompositeKey implements Serializable {
private int column1;
private int column2;
private int column3;
}
，然后在您的实体类中使用@IdClass批注:
and then in your entity class use the @IdClass annotation:
@Entity
@IdClass(CompositeKey.class)
public class EntityExample {
@Id
private int column1;
@Id
private int column2;
@Id
private int column3;
...
...
}
我认为这应该有效.希望能有所帮助，加油！
I think this should work. Hope it helps, cheers!
是的，还有另一种解决方案，@jklee提到的解决方案都可行，这是优先选择的问题.
Yea and there is the other solution, the one that @jklee mentioned, both work, it's a matter of preference.