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/*******************************************************************************
* Copyright (c) 2011 - 2017 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:
* Linda DeMichiel - Java Persistence 2.1
*
******************************************************************************/
package javax.persistence;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static javax.persistence.ConstraintMode.CONSTRAINT;
/**
* Used to specify the handling of foreign key constraints when schema
* generation is in effect. If this annotation is not specified, the
* persistence provider's default foreign key strategy will be used.
*
* The ConstraintMode value is used to specify whether foreign
* key constraints should be generated.
*
* The syntax used in the foreignKeyDefinition element
* should follow the SQL syntax used by the target database for foreign
* key constraints. For example, this may be similar the following:
*
* FOREIGN KEY ( <COLUMN expression> {, <COLUMN expression>}... )
* REFERENCES <TABLE identifier> [
* (<COLUMN expression> {, <COLUMN expression>}... ) ]
* [ ON UPDATE <referential action> ]
* [ ON DELETE <referential action> ]
*
*
* When the ConstraintMode value is
* CONSTRAINT, but the foreignKeyDefinition
* element is not specified, the provider will generate foreign key
* constraints whose update and delete actions it determines most
* appropriate for the join column(s) to which the foreign key
* annotation is applied.
*
* @see JoinColumn
* @see JoinColumns
* @see MapKeyJoinColumn
* @see MapKeyJoinColumns
* @see PrimaryKeyJoinColumn
* @see JoinTable
* @see CollectionTable
* @see SecondaryTable
* @see AssociationOverride
*
* @since Java Persistence 2.1
*/
@Target({})
@Retention(RUNTIME)
public @interface ForeignKey {
/**
* (Optional) The name of the foreign key constraint. If this
* is not specified, it defaults to a provider-generated name.
*/
String name() default "";
/**
* (Optional) Used to specify whether a foreign key constraint should be
* generated when schema generation is in effect.
*
* A value of CONSTRAINT will cause the persistence
* provider to generate a foreign key constraint. If the
* foreignKeyDefinition element is not specified, the
* provider will generate a constraint whose update
* and delete actions it determines most appropriate for the
* join column(s) to which the foreign key annotation is applied.
*
* A value of NO_CONSTRAINT will result in no
* constraint being generated.
*
* A value of PROVIDER_DEFAULT will result in the
* provider's default behavior (which may or may not result
* in the generation of a constraint for the given join column(s).
*/
ConstraintMode value() default CONSTRAINT;
/**
* (Optional) The foreign key constraint definition.
*/
String foreignKeyDefinition() default "";
}