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Manual
15

WHERE clause (JPQL / Criteria API)

JPQL query that retrieves selective objects from the database. Out of the four optional clauses ... of this query defines an iteration over all the Country objects in the database using the c range ... the WHERE predicate. For entity classes with millions of objects in the database there is a huge
FAQ
14

What is the Java Persistence API (JPA)?

. Using plain old Java objects (POJO) to represent persistent data can significantly simplify database ... and objects). ObjectDB is the only database management system with built in support of the Java ... The Java Persistence API (JPA) is a standard API for accessing databases from within Java
JPA Doc
14

JPA Exceptions

to retrieve entity objects from the database. For example, when a required entity object is not found: or ... JPA exceptions are represented by a hierarchy of unchecked exceptions: java.lang.Object java ... , an attempt to update the database with no active transaction is represented by: Database update
Manual
13

Chapter 1 - Quick Tour

on how to start using JPA in your IDE with the ObjectDB object database. Given the simplicity of ObjectDB, that should be quick and easy even for a novice. ... ObjectDB databases and perform basic CRUD operations (Create/Store, Retrieve, Update and Delete) on ObjectDB databases. The example program that this chapter presents manages a simple database
Tutorial
13

Step 3: Define a Spring DAO Component

Operations on the database will be performed by an instance of a Data Access Object (DAO ... - for storing a new Guest entity object in the database. getAllGuests - for retrieving all the existing Guest objects from the database. By using Spring components we can move some work from
Tutorial
13

Step 3: Define a Spring DAO Component

Operations on the database will be performed by an instance of a Data Access Object (DAO ...  Guest entity object in the database. getAllGuests - for retrieving all the existing Guest objects ... .annotation.Transactional; @Component public class GuestDao { // Injected database connection
Manual
13

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 ... . When an entity object is stored in the database every indexed field must contain either null or
Manual
13

Auto Generated Values

number generator for every database. This number generator is used to generate automatic object IDs for entity objects with no primary key fields defined (as explained in the previous section). The same ... a primary key for every new entity object. These generated values are unique at the database level
Tutorial
13

Step 4: Add a Servlet Class

the next tutorial step) - a new Guest entity object is constructed and stored in the database. All the Guest entity objects are retrieved from the database and stored in the request's "guest" attribute ... ServletException, IOException { // Obtain a database connection: EntityManagerFactory
Tutorial
13

Step 4: Add a Servlet Class

is constructed and stored in the database. All the Guest entity objects are retrieved from ... { // Obtain a database connection: EntityManagerFactory emf = (EntityManagerFactory ... ") .forward(request, response); } finally { // Close the database