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Comparison in JPQL and Criteria API

operators (=, <>, ==, !=). Instances of user defined classes (entity classes and embeddable classes ... have the same type and the same primary key value. For embeddable objects, e1 = e2 if e1 and e2

ObjectDB Object Database Features

very efficiently. User Defined Classes Entity classes (@Entity) Embeddable types (@Embeddable

JPA Persistence Unit

A JPA Persistence Unit is a logical grouping of user defined persistable classes (entity classes, embeddable classes and mapped superclasses) with related settings. Defining a persistence unit ... , embeddable classes and mapped superclasses), which are referred to by JPA as managed classes, as


entities in the persistence unit. Since: JPA 2.0 EmbeddableType<X> embeddable(Class<X> cls) Return the metamodel embeddable type representing the embeddable class. Return the metamodel embeddable type representing the embeddable class. Parameters: cls - the type of the represented embeddable class


. May be used to override a relationship mapping from an embeddable within an entity to another entity when the embeddable is on the owning side of the relationship. When used to override a relationship mapping defined by an embeddable class (including an embeddable class embedded within another embeddable

SELECT clause (JPQL / Criteria API)

and user defined embeddable objects) return as results value copies that are not associated

Storing JPA Entity Objects

embedded in containing entity objects. Therefore, if Address is defined as an embeddable class

Entity Management Settings

class, which is not an entity class, mapped super class or embeddable class). The <cascade-persist

Posting Sample Code

/ embeddable classes. Avoid dependency on external libraries. Use a console application with a main method

Paths and Types in JPQL and Criteria API

Instances of user defined persistable classes (entity classes, mapped super classes and embeddable classes) are represented in JPQL by the following types of expressions: Variables - FROM identification variables and SELECT result variables. Parameters - when instances of these classes are assigned

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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