在休眠状态下为表创建唯一索引，其中一列是外键

Question

well I am not that advanced in hibernate and I tried to search a lot, found lots of similar questions but none really applying my case. I have a table TABLE1 which has an index "id" and another table which has as index (TABLE1_ID and NUMBER). Only TABLE1_ID is a foreign key while number doesn't reference anything specific

TABLE 1 has the following hibernate mapping

 <class name="com.test.basic.BASICTABLE1"
    entity-name="com.test.TABLE1" table="TABLE1"
    dynamic-update="true" optimistic-lock="version">
    <id name="id" type="long">
        <column name="id" />
        <generator class="native">
            <param name="sequence">${table1_id.generator.sequence}</param>
        </generator>
    </id>
    <version name="versionNumber" column="verno" generated="always"
        access="field" />
    <property name="column1" column="column1" type="string" length="19"
        not-null="true" access="field" />
 </class>

I am not sure what should be the mapping for the other table. I did it the following way

  <class name="com.test.basic.BASICTABLE2"
    entity-name="com.test.TABLE2" table="table2"
    dynamic-update="true" optimistic-lock="version">

    <composite-id name="id" class="com.test.basic.TABLE1TABLE2Id" >
      <key-property name="TABLE1_ID" column="TABLE1_ID" type="long" />
      <key-property name="NUMBER" column="NUMBER" type="short"/>
    </composite-id>
 </class>

Please note that I created the class TABLE1TABLE2Id after I read somewhere that there should be some intermediate mapping.

I'm sure there's something wrong with TABLE2 mapping (I am not so advanced with hibernate) but when trying to install the app, I am getting the following error

 Foreign key (TABLE1 [id]) must have same number of columns as the referenced primary key (TABLE2 [TABLE1_ID, NUMBER])

I appreciate anybody's help thanks :)

Answer 1

Identity copy (foreign generator)

Finally, you can ask Hibernate to copy the identifier from another associated entity. In the Hibernate jargon, it is known as a foreign generator but the JPA mapping reads better and is encouraged.

The primary key from one entity might be as foreign key be primary key for another table.

@Entity
class MedicalHistory implements Serializable {
  @Id Integer id;

  @MapsId @OneToOne
  @JoinColumn(name = "patient_id")
  Person patient;
}

@Entity
class Person {
  @Id @GeneratedValue Integer id;
}