Copyright (c) 2008 - 2015 Oracle Corporation. All rights reserved.
This program and the accompanying materials are made available under the
terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
which accompanies this distribution.
The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
and the Eclipse Distribution License is available at
http://www.eclipse.org/org/documents/edl-v10.php.
Contributors:
Petros Splinakis - Java Persistence 2.2
Linda DeMichiel - Java Persistence 2.1
Linda DeMichiel - Java Persistence 2.0
/*******************************************************************************
* Copyright (c) 2008 - 2015 Oracle Corporation. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Petros Splinakis - Java Persistence 2.2
* Linda DeMichiel - Java Persistence 2.1
* Linda DeMichiel - Java Persistence 2.0
*
******************************************************************************/
package javax.persistence;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static javax.persistence.ConstraintMode.PROVIDER_DEFAULT;
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 { ... }
See Also: Since: Java Persistence 1.0
/**
* Specifies a primary key column that is used as a foreign key to
* join to another table.
*
* <p> It is used to join the primary table of an entity subclass
* in the {@link InheritanceType#JOINED JOINED} mapping strategy
* to the primary table of its superclass; it is used within a
* {@link SecondaryTable} annotation to join a secondary table
* to a primary table; and it may be used in a {@link OneToOne}
* mapping in which the primary key of the referencing entity
* is used as a foreign key to the referenced entity.
*
* <p> If no <code>PrimaryKeyJoinColumn</code> annotation is
* specified for a subclass in the <code>JOINED</code>
* 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.
*
* <pre>
*
* 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 { ... }
* </pre>
*
* @see SecondaryTable
* @see Inheritance
* @see OneToOne
* @see ForeignKey
*
* @since Java Persistence 1.0
*/
@Repeatable(PrimaryKeyJoinColumns.class)
@Target({TYPE, METHOD, FIELD})
@Retention(RUNTIME)
public @interface PrimaryKeyJoinColumn {
(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).
/**
* (Optional) The name of the primary key column of the current table.
* <p> Defaults to the same name as the primary key column
* of the primary table of the superclass (<code>JOINED</code> mapping strategy); the same
* name as the primary key column of the primary table
* (<code>SecondaryTable</code> mapping); or the same name as the
* primary key column for the table for the referencing entity
* (<code>OneToOne</code> mapping).
*/
String name() default "";
(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).
/**
* (Optional) The name of the primary key column of the table
* being joined to. <p> Defaults to the same name as the primary
* key column of the primary table of the superclass
* (<code>JOINED</code> mapping strategy); the same name as the
* primary key column of the primary table
* (<code>SecondaryTable</code> mapping); or the same name as the
* primary key column for the table for the referencing entity
* (<code>OneToOne</code> mapping).
*/
String referencedColumnName() default "";
(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.
/**
* (Optional) The SQL fragment that is used when generating the
* DDL for the column. This should not be specified for a
* <code>OneToOne</code> primary key association.
* <p> Defaults to the generated SQL to create a column of the
* inferred type.
*/
String columnDefinition() default "";
(Optional) Used to specify or control the generation of a
foreign key constraint for the primary key join column
when table generation is in effect. If
this element is not specified, the persistence provider's
default foreign key strategy will apply.
@since Java Persistence 2.1
/**
* (Optional) Used to specify or control the generation of a
* foreign key constraint for the primary key join column
* when table generation is in effect. If
* this element is not specified, the persistence provider's
* default foreign key strategy will apply.
*
* @since Java Persistence 2.1
*/
ForeignKey foreignKey() default @ForeignKey(PROVIDER_DEFAULT);
}