javax.persistence.PrimaryKeyJoinColumn Maven / Gradle / Ivy
/*
* 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 {@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.
*
* 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 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).
*
* @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).
*
* @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.
*
* @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.
*
* @return The foreign key specification
*/
ForeignKey foreignKey() default @ForeignKey();
}