/*
* 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.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.ElementType.FIELD;
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 Also: Since: Java Persistence 1.0
/**
* Specifies a column for joining an entity association or element collection. If the <code>JoinColumn</code>
* annotation itself is defaulted, a single join column is assumed and the default values apply.
* <p>
* <pre>
* 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;}
* </pre>
*
* @see ManyToOne
* @see OneToMany
* @see OneToOne
* @see JoinTable
* @see CollectionTable
* @since Java Persistence 1.0
*/
@Target({FIELD})
@Retention(RUNTIME)
@Repeatable(JoinColumns.class)
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.
Returns: The name
/**
* (Optional) The name of the foreign key column. The table in which it is found depends upon the context.
* <ul>
* <li>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.
* <li>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.
* <li>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.
* <li>If the join is for an element collection, the foreign key is in a collection table.
* </ul>
* <p>
* 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.
Returns: The referenced col name
/**
* (Optional) The name of the column referenced by this foreign key column.
* <ul>
* <li>When used with entity relationship mappings other than the cases described here, the referenced
* column is in the table of the target entity.
* <li>When used with a unidirectional OneToMany foreign key mapping, the referenced column is in the
* table of the source entity.
* <li>When used inside a <code>JoinTable</code> 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.
* <li>When used in a <code>CollectionTable</code> mapping, the referenced column is in the table of the
* entity containing the collection.
* </ul>
* <p>
* 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.
Returns: whether this col is unique
/**
* (Optional) Whether the property is a unique key. This is a shortcut for the
* <code>UniqueConstraint</code> 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.
Returns: Whether this col is nullable
/**
* (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.
Returns: Whether insertable
/**
* (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.
Returns: Whether updateable
/**
* (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.
Returns: The column definition
/**
* (Optional) The SQL fragment that is used when generating the DDL for the column.
* <p>
* 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.
Returns: Table
/**
* (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.
* <p>
* Default:
* <ul>
* <li>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.
* <li>If the join is for a unidirectional OneToMany mapping using a foreign key mapping strategy, the
* name of the table of the target entity.
* <li>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.
* <li>If the join is for an element collection, the name of the collection table.
* </ul>
*
* @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.
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();
}