javax.persistence.PrimaryKeyJoinColumn - JPA annotation
javax.persistence
Annotation PrimaryKeyJoinColumn
- Target:
- Classes and fields (including property get methods)
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:
- JPA 1.0
- See Also:
-
SecondaryTable
-
Inheritance
-
OneToOne
OneToOne
primary key association. Defaults to the generated SQL to create a column of the inferred type.
- Default value:
- ""
- Since:
- JPA 1.0
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).
- Default value:
- ""
- Since:
- JPA 1.0
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).
- Default value:
- ""
- Since:
- JPA 1.0