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/*
* 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.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
/**
* Specifies a column for joining an entity association or element collection. If the JoinColumn
* annotation itself is defaulted, a single join column is assumed and the default values apply.
*
*
* Example:
*
* @ManyToOne
* @JoinColumn(name="ADDR_ID")
* public Address getAddress() { return address; }
*
*
* Example: unidirectional one-to-many association using a foreign key mapping
*
* // In Customer class
* @OneToMany
* @JoinColumn(name="CUST_ID") // join column is in table for Order
* public Set<Order> getOrders() {return orders;}
*
* @see ManyToOne
* @see OneToMany
* @see OneToOne
* @see JoinTable
* @see CollectionTable
* @since Java Persistence 1.0
*/
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface JoinColumn
{
/**
* (Optional) The name of the foreign key column. The table in which it is found depends upon the context.
*
* - If the join is for a OneToOne or ManyToOne mapping using a foreign key mapping strategy, the
* foreign key column is in the table of the source entity or embeddable.
*
- If the join is for a unidirectional OneToMany mapping using a foreign key mapping strategy, the
* foreign key is in the table of the target entity.
*
- If the join is for a ManyToMany mapping or for a OneToOne or bidirectional ManyToOne/OneToMany
* mapping using a join table, the foreign key is in a join table.
*
- If the join is for an element collection, the foreign key is in a collection table.
*
*
* Default (only applies if a single join column is used): The concatenation of the following: the name of
* the referencing relationship property or field of the referencing entity or embeddable class; "_"; the
* name of the referenced primary key column. If there is no such referencing relationship property or
* field in the entity, or if the join is for an element collection, the join column name is formed as the
* concatenation of the following: the name of the entity; "_"; the name of the referenced primary key
* column.
* @return The name
*/
String name() default "";
/**
* (Optional) The name of the column referenced by this foreign key column.
*
* - When used with entity relationship mappings other than the cases described here, the referenced
* column is in the table of the target entity.
*
- When used with a unidirectional OneToMany foreign key mapping, the referenced column is in the
* table of the source entity.
*
- When used inside a
JoinTable annotation, the referenced key column is in the entity
* table of the owning entity, or inverse entity if the join is part of the inverse join definition.
* - When used in a
CollectionTable mapping, the referenced column is in the table of the
* entity containing the collection.
*
*
* Default (only applies if single join column is being used): The same name as the primary key column of
* the referenced table.
* @return The referenced col name
*/
String referencedColumnName() default "";
/**
* (Optional) Whether the property is a unique key. This is a shortcut for the
* UniqueConstraint annotation at the table level and is useful for when the unique key
* constraint is only a single field. It is not necessary to explicitly specify this for a join column
* that corresponds to a primary key that is part of a foreign key.
* @return whether this col is unique
*/
boolean unique() default false;
/**
* (Optional) Whether the foreign key column is nullable.
* @return Whether this col is nullable
*/
boolean nullable() default true;
/**
* (Optional) Whether the column is included in SQL INSERT statements generated by the persistence
* provider.
* @return Whether insertable
*/
boolean insertable() default true;
/**
* (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence
* provider.
* @return Whether updateable
*/
boolean updatable() default true;
/**
* (Optional) The SQL fragment that is used when generating the DDL for the column.
*
* Defaults to the generated SQL for the column.
* @return The column definition
*/
String columnDefinition() default "";
/**
* (Optional) The name of the table that contains the column. If a table is not specified, the column is
* assumed to be in the primary table of the applicable entity.
*
* Default:
*
* - If the join is for a OneToOne or ManyToOne mapping using a foreign key mapping strategy, the name
* of the table of the source entity or embeddable.
*
- If the join is for a unidirectional OneToMany mapping using a foreign key mapping strategy, the
* name of the table of the target entity.
*
- If the join is for a ManyToMany mapping or for a OneToOne or bidirectional ManyToOne/OneToMany
* mapping using a join table, the name of the join table.
*
- If the join is for an element collection, the name of the collection table.
*
* @return Table
*/
String table() 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();
}