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Defining a JPA Entity Class

To be able to store Point objects in the database using JPA we need to define an entity class. A JPA entity class is a POJO (Plain Old Java Object) class, i.e. an ordinary Java class that is marked (annotated) as having the ability to represent objects in the database. Conceptually this is similar

Database Schema Evolution

of an entity class are detected by ObjectDB. New entity objects have to be stored in the new class schema, and old entity objects, which were stored previously in the old class schema ... that enables transparent use of old entity objects after schema change. When an entity object

JPA Lifecycle Events

class is also invoked for entity objects of the subclasses unless that callback method is overridden ... call EntityManager or Query methods and should not access any other entity objects. If a callback method ... MyListener { @PrePersist void onPrePersist(Object o) {} @PostPersist void onPostPersist(Object


Existing entity objects can be updated, as explained in chapter 2, by: Retrieving the entity objects into an EntityManager. Updating the relevant entity object fields within an active transaction ... an alternative way of updating entity objects. Unlike SELECT queries, which are used to retrieve data from

JPA Query Structure (JPQL / Criteria)

classes and objects. For example, a JPQL query can retrieve and return entity objects rather than just field values from database tables, as with SQL. That makes JPQL more object oriented friendly ... JPQL Query The following query retrieves all the Country objects in the database: SELECT c FROM

Setting and Tuning of JPA Queries

since the setter methods in Query and TypedQuery support method chaining (by returning the query object ... uses automatic optimistic locking to prevent concurrent changes to entity objects by multiple users ... that has to be applied on all the result objects that the query retrieves. For example, the following query

Index Definition

Querying without indexes requires iteration over entity objects in the database one by one. This may take a significant amount of time if many entity objects have to be examined. Using proper indexes the iteration can be avoided and complex queries over millions of objects can be executed quickly

WHERE clause (JPQL / Criteria API)

JPQL query that retrieves selective objects from the database. Out of the four optional clauses ... over all the Country objects in the database using the c range variable. Before passing these Country objects to the SELECT clause for collecting as query results, the WHERE clause gets an opportunity

Apache License, Version 2.0, January 2004

to software source code, documentation source, and configuration files. "Object" form shall mean any form ... to compiled object code, generated documentation, and conversions to other media types. "Work" shall mean the work of authorship, whether in Source or Object form, made available under the License, as

[ODB1] Chapter 1 - About ObjectDB

ObjectDB for Java/JDO is a powerful Object Database Management System (ODBMS) written entirely in ... of them. ObjectDB is an Object Database Developing object oriented applications with ObjectDB is easier and much more effective because the content of the database is application objects. Whereas, working

Getting Started

ObjectDB is very easy to use. Follow the Getting Started Tutorial and the Quick Tour manual chapter and in minutes you may be able to write and run first Java programs against ObjectDB.

Prior knowledge or experience in database programming (SQL, JDBC, ORM, JPA, etc.) is not required, but some background in using the Java language is essential.

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