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JPA Primary Key

Every entity object that is stored in the database has a primary key. Once assigned, the primary ... an object database, ObjectDB supports implicit object IDs, so an explicitly defined primary key is not required. But ObjectDB also supports explicit standard JPA primary keys, including composite primary

Chapter 2 - JPA Entity Classes

Explains how to define and use JPA entity classes and other JPA persistable types.

ObjectDB Object Database Features

support of the JPA and JDO APIs. Fundamental features of relational databases (e.g. primary keys, derived ... methods and listener classes. Primary Keys Support of primary keys in ObjectDB is unique compared to other Objec-Oriented Databases. Primary Key Modes Hidden - primary key is automatically managed by

JDO Predefined ID Classes

An object ID is a combination of a persistence capable class and a primary key. It provides ... for persistence capable classes with a simple single field primary key: Object IDs are used in many ... but should not be used as the type of a primary key field in a persistence capable class. For example

Auto Generated Values

generated for that field. This is primarily intended for primary key fields but ObjectDB also supports ... for entity objects with no primary key fields defined (as explained in the previous section). The same number generator is also used to generate numeric values for primary key fields annotated by

2.7.3_03 Erroneous "Attempt to modify a primary key of a managed object"

key of a managed object", but my application is not trying to change the primary key.  (ObjectDB ... attached. Thanks. Could you please provide details on the primary key of JdoBlob2? Is it composite ... a combination of class + primary key and therefore it seems a bit strange to use it as the type

Retrieving JPA Entity Objects

of entity classes and to keep them simple as possible. Retrieval by Class and Primary Key Every entity object can be uniquely identified and retrieved by the combination of its class and its primary key ... whose primary key is 1: Employee employee = em.find(Employee.class, 1); Casting of the retrieved

Defining a JPA Entity Class

for persistent fields, how to define and use a primary key and what a version field is and how to use it. If you are already familiar with JPA you might have noticed that the Point entity class has no primary key ... defined primary key is not required. On the other hand, ObjectDB also supports explicit JPA primary

JPA Entity Fields

(Mapped By) fields Primary key (ID) fields Version field The first three groups (transient, persistent ... two groups (primary key and version fields) can only be used in entity classes. Primary key fields are discussed in the Primary Key section. Transient Fields Transient entity fields are fields

problem when primary key value is zero

and recommendations, in particular there are some primary keys with value == 0. These cause problems for objectDB, typically "JPA Unexpected argument as primary key". When using eclipselink, there is a workaround ... have a zero value in primary key column -->