javax.persistence
Annotation Type JoinColumn
@Target(value={METHOD,FIELD})
@Retention(value=RUNTIME)
public @interface JoinColumn
Is used to specify a mapped column for joining an entity association.
- Author:
- Emmanuel Bernard
Optional Element Summary |
String |
columnDefinition
The SQL fragment that is used when generating the DDL for the column. |
boolean |
insertable
Whether the column is included in SQL INSERT statements generated by the persistence provider |
String |
name
The name of the foreign key column. |
boolean |
nullable
Whether the foreign key column is nullable |
String |
referencedColumnName
The name of the column referenced by this foreign key column. |
String |
table
The name of the table that contains the column. |
boolean |
unique
Whether the property is a unique key. |
boolean |
updatable
Whether the column is included in SQL UPDATE statements generated by the persistence provider |
name
public abstract String name
- 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 Many- ToOne mapping, the foreign key column is in the table of the source entity.
If the join is for a ManyToMany, the foreign key is in a join 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; "_"; the name of the referenced primary
key column. If there is no such referencing relationship property or field in the entity, 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.
- Default:
- ""
referencedColumnName
public abstract String referencedColumnName
- The name of the column referenced by this foreign key column. When used with relationship mappings,
the referenced column is in the table of the target 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. Default (only applies if single join column is being used):
The same name as the primary key column of the referenced table.
- Default:
- ""
unique
public abstract boolean unique
- 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.
- Default:
- false
nullable
public abstract boolean nullable
- Whether the foreign key column is nullable
- Default:
- true
insertable
public abstract boolean insertable
- Whether the column is included in SQL INSERT statements generated by the persistence provider
- Default:
- true
updatable
public abstract boolean updatable
- Whether the column is included in SQL UPDATE statements generated by the persistence provider
- Default:
- true
columnDefinition
public abstract String columnDefinition
- The SQL fragment that is used when generating the DDL for the column.
Defaults to the generated SQL for the column.
- Default:
- ""
table
public abstract String table
- 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:
- ""