Note: This ORM/SQL annotation is silently ignored by ObjectDB

398 words

javax.persistence.OrderColumn - JPA annotation

javax.persistence
Annotation OrderColumn

Target:
Fields (including property get methods)
Specifies a column that is used to maintain the persistent order of a list. The persistence provider is responsible for maintaining the order upon retrieval and in the database. The persistence provider is responsible for updating the ordering upon flushing to the database to reflect any insertion, deletion, or reordering affecting the list.

The OrderColumn annotation is specified on a OneToMany or ManyToMany relationship or on an element collection. The OrderColumn annotation is specified on the side of the relationship that references the collection that is to be ordered. The order column is not visible as part of the state of the entity or embeddable class.

The OrderBy annotation should be used for ordering that is visible as persistent state and maintained by the application. The OrderBy annotation is not used when OrderColumn is specified.

The order column must be of integral type. The persistence provider maintains a contiguous (non-sparse) ordering of the values of the order column when updating the association or element collection. The order column value for the first element is 0.

Example:

    @Entity
    public class CreditCard {
 
       @Id long ccNumber;
 
       @OneToMany  // unidirectional
       @OrderColumn
       List<CardTransaction> transactionHistory;
       ...
    }

Since:
JPA 2.0
See Also:
OrderBy
(Optional) The SQL fragment that is used when generating the DDL for the column.
(Optional) The SQL fragment that is used when generating the DDL for the column. Defaults to generated SQL to create a column of the inferred type.
Default value:
""
Since:
JPA 2.0
boolean insertable
(Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.
(Optional) Whether the column is included in SQL INSERT statements generated by the persistence provider.
Default value:
true
Since:
JPA 2.0
String name
(Optional) The name of the ordering column.
(Optional) The name of the ordering column. Defaults to the concatenation of the name of the referencing property or field; "_"; "ORDER".
Default value:
""
Since:
JPA 2.0
boolean nullable
(Optional) Whether the database column is nullable.
(Optional) Whether the database column is nullable.
Default value:
true
Since:
JPA 2.0
boolean updatable
(Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.
(Optional) Whether the column is included in SQL UPDATE statements generated by the persistence provider.
Default value:
true
Since:
JPA 2.0

This documentation page is derived (with some adjustments) from the open source JPA 2 RI (EclipseLink)
and is available under the terms of the Eclipse Public License, v. 1.0 and Eclipse Distribution License, v. 1.0.
Object Relational Mapping (ORM) JPA 2 providers include Hibernate, EclipseLink, TopLink, OpenJPA and DataNucleus.
Object DB is not an ORM JPA implementation but an Object Database for Java with built in JPA 2 support.