Note: This ORM/SQL annotation is silently ignored by ObjectDB

428 words

javax.persistence.PrimaryKeyJoinColumn - JPA annotation

javax.persistence
Annotation PrimaryKeyJoinColumn

Target:
Classes and fields (including property get methods)
Specifies a primary key column that is used as a foreign key to join to another table.

It is used to join the primary table of an entity subclass in the JOINED mapping strategy to the primary table of its superclass; it is used within a SecondaryTable annotation to join a secondary table to a primary table; and it may be used in a OneToOne mapping in which the primary key of the referencing entity is used as a foreign key to the referenced entity.

If no PrimaryKeyJoinColumn annotation is specified for a subclass in the JOINED mapping strategy, the foreign key columns are assumed to have the same names as the primary key columns of the primary table of the superclass.

Example: Customer and ValuedCustomer subclass

    @Entity
    @Table(name="CUST")
    @Inheritance(strategy=JOINED)
    @DiscriminatorValue("CUST")
    public class Customer { ... }
 
    @Entity
    @Table(name="VCUST")
    @DiscriminatorValue("VCUST")
    @PrimaryKeyJoinColumn(name="CUST_ID")
    public class ValuedCustomer extends Customer { ... }

Since:
JPA 1.0
See Also:
SecondaryTable
Inheritance
OneToOne
(Optional) The SQL fragment that is used when generating the DDL for the column.
(Optional) The SQL fragment that is used when generating the DDL for the column. This should not be specified for a OneToOne primary key association.

Defaults to the generated SQL to create a column of the inferred type.

Default value:
""
Since:
JPA 1.0
String name
(Optional) The name of the primary key column of the current table.
(Optional) The name of the primary key column of the current table.

Defaults to the same name as the primary key column of the primary table of the superclass (JOINED mapping strategy); the same name as the primary key column of the primary table (SecondaryTable mapping); or the same name as the primary key column for the table for the referencing entity (OneToOne mapping).

Default value:
""
Since:
JPA 1.0
(Optional) The name of the primary key column of the table being joined to.
(Optional) The name of the primary key column of the table being joined to.

Defaults to the same name as the primary key column of the primary table of the superclass (JOINED mapping strategy); the same name as the primary key column of the primary table (SecondaryTable mapping); or the same name as the primary key column for the table for the referencing entity (OneToOne mapping).

Default value:
""
Since:
JPA 1.0

This documentation page is derived (with some adjustments) from the open source JPA 2 RI (EclipseLink)
and is available under the terms of the Eclipse Public License, v. 1.0 and Eclipse Distribution License, v. 1.0.
Object Relational Mapping (ORM) JPA 2 providers include Hibernate, EclipseLink, TopLink, OpenJPA and DataNucleus.
Object DB is not an ORM JPA implementation but an Object Database for Java with built in JPA 2 support.