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Running JPA Queries

when exactly one result object is expected. Query.getResultList - for general use in any other case ... - for use when exactly one result object is expected. TypedQuery.getResultList - for general use in any ... (with getResultList) The following query retrieves all the Country objects in the database. The query


As explained in chapter 2, entity objects can be deleted from the database by: Retrieving the entity objects into an EntityManager. Removing these objects from the EntityManager within an active ... an alternative way for deleting entity objects. Unlike SELECT queries, which are used to retrieve data from

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

JPA Entity Fields

otherwise (e.g. by using the @Transient annotation). Storing an entity object in the database does not store methods or code. Only the persistent state of the entity object, as reflected by its persistent ... . When an entity object is stored in the database every persistent field must contain either null or a value

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


. This exception contains a nested JDOOptimisticVerificationException for each object that failed ... .0 void deletePersistent(Object pc) Delete the persistent instance from the data store. Delete ... . The data store object will be removed at commit. Unlike makePersistent, which makes the closure

[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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