Package javax.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 strategy and the discriminator column are only specified in 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:
Java Persistence 1.0
See Also:

  • 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.

  • 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:
      ""

    • length

      int length
      (Optional) The column length for String-based discriminator types. Ignored for other discriminator types.
      Default:
      31