DiscriminatorColumn (EclipseLink 2.6.2, API Reference)

EclipseLink 2.6.2, API Reference

All Classes

Summary:
Required |
Optional

Detail:
Element

```
@Target(value=TYPE)
@Retention(value=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 { ... }
 
```
See Also:
DiscriminatorValue
Since:

Java Persistence 1.0

Optional Element Summary

Optional Elements
Modifier and Type	Optional Element and Description
`java.lang.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.
`java.lang.String`	`name` (Optional) The name of column to be used for the discriminator.

- Element Detail
  - name
```
public abstract java.lang.String name
```
    (Optional) The name of column to be used for the discriminator.
    
    Default:
    
    "DTYPE"
  - discriminatorType
```
public abstract DiscriminatorType discriminatorType
```
    (Optional) The type of object/column to use as a class discriminator. Defaults to DiscriminatorType.STRING.
    
    Default:
    
    javax.persistence.DiscriminatorType.STRING
  - columnDefinition
```
public abstract java.lang.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
```
public abstract int length
```
    (Optional) The column length for String-based discriminator types. Ignored for other discriminator types.
    
    Default:
    
    31

EclipseLink 2.6.2, API Reference

All Classes

Summary:
Required |
Optional

Detail:
Element