javax.persistence

Annotation Type PrimaryKeyJoinColumn

@Target(value={TYPE,METHOD,FIELD})
 @Retention(value=RUNTIME)
public @interface PrimaryKeyJoinColumn

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 { ... }
 

Since:

Java Persistence 1.0

See Also:

SecondaryTable, Inheritance, OneToOne

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String	columnDefinition (Optional) The SQL fragment that is used when generating the DDL for the column.
ForeignKey	foreignKey (Optional) The foreign key constraint specification for the join column.
String	name (Optional) The name of the primary key column of the current table.
String	referencedColumnName (Optional) The name of the primary key column of the table being joined to.

Element Detail

name

public abstract String 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 (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

Default:

""

referencedColumnName

public abstract String referencedColumnName

(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

Default:

""

columnDefinition

public abstract String columnDefinition

(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

Default:

""

foreignKey

public abstract ForeignKey foreignKey

(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

Default:

@javax.persistence.ForeignKey