如何将两个外键映射到Hibernate中的同一主键列(一对一)? [英] How to map two foreign keys mapping to the same primary key column in Hibernate (one-to-one)?
问题描述
我是Java和Hibernate的新手,我正在尝试在Hibernate中映射以下场景(使用批注).
I am new to Java and Hibernate and I am trying to map the following scenario in Hibernate (using annotations).
我正在处理以下两个表(与某些ETL类型的任务有关).
I am dealing with the following two tables ( related to some ETL type of tasks).
任务
| -TaskId
| -SourceDatabase(从FK到Databases表)
| -TargetDatabase(数据库表FK)
Tasks
|-TaskId
|-SourceDatabase (FK to the Databases table)
|-TargetDatabase (FK to the Databases table)
数据库
| -DatabaseId(PK)
| -TaskId(FK到Tasks表)
|-其他数据库详细信息.
Databases
|-DatabaseId (PK)
|-TaskId (FK to the Tasks table)
|-Other database details.
每个任务都有一个sourceDatabase和一个targetDatabase.此外,每个数据库都与仅一个任务相关. 如何在Hibernate中使用一对一映射来映射到该模型.
Each task has a sourceDatabase and a targetDatabase. Also each Database is related to only one Task. How can I map to this model in Hibernate using one-to-one mapping.
@Entity
public class Task implements Serializable
{
@Id
int taskId;
//How to map using one-to-one mapping??
Database sourceDB;
//how to map using one-to-one mapping??
Database targetDB;
}
@Entity
public class Database implements Serializable
{
@Id
int databaseId;
//How to map using one-to-one mapping??
Task task;
}
我已从上述代码示例中删除了所有不必要的代码. 在此先感谢!
I have removed all unnecessary code from the above code sample. Thanks in advance!!
推荐答案
据我了解,您与各自的外键具有3个单独的一对一关系,因此您可以将它们映射为普通的一对一关系.一种关系:
As far as I understand, you have 3 separate one-to-one relationships with their respective foreign keys, so you can map them as normal one-to-one relationships:
@Entity
public class Task implements Serializable
{
...
@OneToOne @JoinColumn(name = "SourceDatabase")
Database sourceDB;
@OneToOne @JoinColumn(name = "TargetDatabase")
Database targetDB;
}
@Entity
public class Database implements Serializable
{
...
@OneToOne @JoinColumn(name = "TaskId")
Task task;
}
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