Module jakarta.persistence

Package jakarta.persistence

Annotation Interface DiscriminatorColumn

@Target(TYPE)
@Retention(RUNTIME)
public @interface DiscriminatorColumn

Specifies the discriminator column for the SINGLE_TABLE and JOINED inheritance mapping strategies.

The mapping strategy and discriminator column are only specified for the root of an entity class hierarchy or subhierarchy in which a different inheritance strategy is applied.

If the DiscriminatorColumn annotation is missing, and a discriminator column is required, the name of the discriminator column defaults to "DTYPE" and the discriminator type to DiscriminatorType.STRING.

Example:

@Entity
@Table(name = "CUST")
@Inheritance(strategy = SINGLE_TABLE)
@DiscriminatorColumn(name = "DISC", discriminatorType = STRING, length = 20)
public class Customer { ... }

@Entity
public class ValuedCustomer extends Customer { ... }

Since:

1.0

See Also:

• DiscriminatorValue
• DiscriminatorType

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
String	columnDefinition	(Optional) The SQL fragment that is used when generating the DDL for the discriminator column.
DiscriminatorType	discriminatorType	(Optional) The type of object/column to use as a class discriminator.
int	length	(Optional) The column length for String-based discriminator types.
String	name	(Optional) The name of column to be used for the discriminator.
String	options	(Optional) A SQL fragment appended to the generated DDL which declares this column.

Element Details

name

String name

(Optional) The name of column to be used for the discriminator.

Default:

"DTYPE"

discriminatorType

DiscriminatorType discriminatorType

(Optional) The type of object/column to use as a class discriminator. Defaults to DiscriminatorType.STRING.

Default:

STRING

columnDefinition

String columnDefinition

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

Defaults to the provider-generated SQL to create a column of the specified discriminator type.

Default:

""

options

String options

(Optional) A SQL fragment appended to the generated DDL which declares this column. May not be used in conjunction with columnDefinition().

Since:

3.2

Default:

""

length

int length

(Optional) The column length for String-based discriminator types. Ignored for other discriminator types.

Default:

31