javax.persistence
Annotation Type MapKeyColumn

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

The MapKeyColumn annotation is used to specify the mapping for the key column of a map whose map key is a basic type. If the name element is not specified, it defaults to the concatenation of the fol- lowing: the name of the referencing relationship field or property; "_"; "KEY".

Since:

JPA 2.0 version.

Author:

Florent Benoit

See Also:

JPA 2.0 specification

Optional Element Summary

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.
int	length (Optional) The column length.
String	name (Optional) The name of the map key col- umn.
boolean	nullable (Optional) Whether the database column is nullable.
int	precision (Optional) The precision for a decimal (exact numeric) column.
int	scale (Optional) The scale for a decimal (exact numeric) column.
String	table (Optional) The name of the table that contains the column.
boolean	unique (Optional) Whether the column is a unique key.
boolean	updatable (Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.

name

public abstract String name

(Optional) The name of the map key col- umn. The table in which it is found depends upon the context. If the map key is for an element collection, the map key column is in the collection table for the map value. If the map key is for a ManyToMany entity relationship or for a OneToMany entity relationship using a join table, the map key column is in a join table. If the map key is for a OneTo- Many entity relationship using a foreign key mapping strategy, the map key col- umn is in the table of the entity that is the value of the map.

Default:

""

unique

public abstract boolean unique

(Optional) Whether the column 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 corresponds to only a sin- gle column. This constraint applies in addition to any constraint entailed by primary key mapping and to constraints specified at the table level.

Default:

false

nullable

public abstract boolean nullable

(Optional) Whether the database column is nullable.

Default:

false

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 String columnDefinition

(Optional) The SQL fragment that is used when generating the DDL for the column.

Default:

""

table

public abstract String table

(Optional) The name of the table that contains the column.

Default:

""

length

public abstract int length

(Optional) The column length. (Applies only if a string-valued column is used.)

Default:

255

precision

public abstract int precision

(Optional) The precision for a decimal (exact numeric) column. (Applies only if a decimal column is used.)

Default:

0

scale

public abstract int scale

(Optional) The scale for a decimal (exact numeric) column. (Applies only if a dec- imal column is used.)

Default:

0