javax.persistence
Annotation Type JoinColumn


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

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;}
 

Since:
Java Persistence 1.0
See Also:
ManyToOne, OneToMany, OneToOne, JoinTable, CollectionTable

Optional Element Summary
 java.lang.String columnDefinition
          (Optional) The SQL fragment that is used when generating the DDL for the column.
 boolean insertable
          (Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.
 java.lang.String name
          (Optional) The name of the foreign key column.
 boolean nullable
          (Optional) Whether the foreign key column is nullable.
 java.lang.String referencedColumnName
          (Optional) The name of the column referenced by this foreign key column.
 java.lang.String table
          (Optional) The name of the table that contains the column.
 boolean unique
          (Optional) Whether the property is a unique key.
 boolean updatable
          (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.
 

name

public abstract java.lang.String name
(Optional) The name of the foreign key column. The table in which it is found depends upon the context.

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.

Default:
""

referencedColumnName

public abstract java.lang.String referencedColumnName
(Optional) The name of the column referenced by this foreign key column.

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
(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.

Default:
false

nullable

public abstract boolean nullable
(Optional) Whether the foreign key column is nullable.

Default:
true

insertable

public abstract boolean insertable
(Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.

Default:
true

updatable

public abstract boolean updatable
(Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.

Default:
true

columnDefinition

public abstract java.lang.String columnDefinition
(Optional) 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 java.lang.String 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.

Default:

Default:
""


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Generated on 10-February-2011 12:41


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