ObjectDB ObjectDB
Home » JPA Reference » Annotations » Relationships » ManyToOne » ManyToOne.optional - JPA annotation element
JPA Reference

ManyToOne.optional - JPA annotation element

Annotation Element
javax.persistence.ManyToOne
boolean optional

(Optional) Whether the association is optional. If set to false then a non-null relationship must always exist.
Default value:
true
Since:
JPA 1.0
< ManyToOne^ ManyToOneOneToMany >
ObjectDB Database Getting Started Support
DBMS Features Quick Tour with JPA ObjectDB FAQ
Editions and Prices JPA Console Tutorial ObjectDB Manual
Licence Web App Tutorial Forum
Attributions Java EE JPA Tutorial Issue Tracking
Privacy Spring MVC JPA Tutorial Website Search
Terms of Use Download ObjectDB Contact Us

Which JPA is Faster?

 

See a comparison of Hibernate, EclipseLink, OpenJPA, DataNucleus, MySQL, PostgreSQL, Derby, HSQLDB, DB4O by Versant, H2 Database, SQLite and ObjectDB

in the JPA Benchmark.

Copyright © 2003, 2010, 2024  ObjectDB Software, all rights reserved. The JPA API Reference Documentation (JavaDoc) on this website 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. The JDO API Reference Documentation (JavaDoc) on this website is derived with some adjustments from the JDO 2.2 API and is available under the terms of the Apache License, v. 2.0. Images on this website are available under these licecnes. Documentation on this website explains how to use JPA in the context of the ObjectDB Object Database but mostly relevant also for ORM JPA implementations, such as Hibernate (and HQL), EclipseLink, TopLink, OpenJPA and DataNucleus. ObjectDB is not an ORM JPA implementation but an Object Database (ODBMS) for Java with built in JPA 2 support.