/*
* Copyright (c) 2008, 2009, 2011 Oracle, Inc. 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.
*/
package javax.persistence;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
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.
* <p>
* <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
* @since Java Persistence 1.0
*/
@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).
Returns: name
/**
* (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 (<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).
*
* @return name
*/
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).
Returns: ref col name
/**
* (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 (<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).
*
* @return ref col name
*/
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.
Returns: column def
/**
* (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. Defaults to the generated SQL to create
* a column of the inferred type.
*
* @return column def
*/
String columnDefinition() default "";
(Optional) The foreign key constraint specification for the join column. This is used only if table
generation is in effect. Default is provider defined.
Returns: The foreign key specification
/**
* (Optional) The foreign key constraint specification for the join column. This is used only if table
* generation is in effect. Default is provider defined.
*
* @return The foreign key specification
*/
ForeignKey foreignKey() default @ForeignKey();
}