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What is ObjectDB?

ObjectDB is an Object Oriented Database Management System (ODBMS). It provides all the standard ... , etc.), but it uses an object oriented model to store and manage data. You can easily store ordinary objects (and graphs of objects) in an ObjectDB database directly. There's no need to define tables or

Query Parameters in JPA

) The following method retrieves a Country object from the database by its name: public Country ... ("name", name).getSingleResult(); } The WHERE clause reduces the query results to Country objects ... other query elements) are represented by objects (of type ParameterExpression or its super interface

JPA Exceptions

JPA exceptions are represented by a hierarchy of unchecked exceptions: java.lang.Object java ... ) . For example, if a transaction fails because of an attempt to store a new entity object with a primary key that is already in use by another existing entity object, the nested exception is: Other common

JPA Persistable Types

class can only be stored in the database as embedded objects, i.e. as part of a containing entity object. A class is declared as embeddable by marking it with the Embeddable annotation: @Embeddable ... country; String zip; } Instances of embeddable classes are always embedded in other entity objects

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


results and the lowest known common denominator of all the result objects is Object. When a more specific ... , the same JPQL query which retrieves all the Country objects in the database is represented by both q1 ... only Country objects), a TypedQuery is preferred. There is another advantage of using TypedQuery in

Step 3: Add a Main Class

to store Point objects in the database and then retrieve them from the database. Use copy and paste ... (); // Store 1000 Point objects in the database: em.getTransaction().begin ... ); } em.getTransaction().commit(); // Find the number of Point objects in

Step 3: Add a Main Class

In this step we will add a main class to the project to store and retrieve Point objects from ... .createEntityManager(); // Store 1000 Point objects in the database: em.getTransaction().begin ... of Point objects in the database: Query q1 = em.createQuery("SELECT COUNT(p) FROM Point p

Which API should I use - JPA or JDO?

You can use ObjectDB with either the Java Persistence API (JPA) or the Java Data Objects (JDO) API ... code. When to prefer JDO JDO might be preferred when portability to other object databases is more important than general portability to both object and relational databases. JPA is designated

JDO Predefined ID Classes

An object ID is a combination of a persistence capable class and a primary key. It provides a unique representation of a persistent object. The following classes serve as predefined ID classes for persistence capable classes with a simple single field primary key: Object IDs are used in many

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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