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.
Internal Website Search1-10 of 200 resultsRefresh
The Java Persistence API (JPA) provides various ways to retrieve objects from the database. The retrieval of objects does not require an active transaction because it does not change the content of the database. The persistence context serves as a cache of retrieved entity objects. If a requested
All about Is ObjectDB better than Object Relational Mapping (ORM)? in Java/JPA database - explanations, examples, references, links and related information.
Entity objects are in-memory instances of entity classes (persistable user defined classes), which can represent physical objects in the database. Managing an ObjectDB Object Database using JPA requires using entity objects for many operations, including storing, retrieving, updating and deleting
Detached entity objects are objects in a special state in which they are not managed by any EntityManager but still represent objects in the database. Compared to managed entity objects, detached objects are limited in functionality: Many JPA methods do not accept detached objects (e.g. lock
New entity objects can be stored in the database either explicitly by invoking the persist method ... .getTransaction().commit(); The Employee instance is constructed as an ordinary Java object and its initial state is New. An explicit call to persist associates the object with an owner EntityManager em
Existing entity objects can be deleted from the database either explicitly by invoking the remove method or implicitly as a result of a cascade operation. Explicit Remove In order to delete an object ... (); The entity object is physically deleted from the database when the transaction is committed. Embedded
attributes, grouping queries and aggregate queries) which are usually missing from Object Oriented Databases are also supported by ObjectDB. The combination of Object Database features ... . Up to 9,223,372,036,854,775,808 entity objects per database file. Unlimited database connections (limited
Modifying existing entity objects that are stored in the database is based on transparent ... Once an entity object is retrieved from the database (no matter which way) it can simply be modified in memory ... (); The entity object is physically updated in the database when the transaction is committed
This chapter describes how to use ObjectDB to manage database objects. 6.1 Making Objects Persistent In JDO applications, every object in memory is either a persistent object, i.e. represents some database content, or a transient object, i.e. not related to any database. Storing Objects Explicitly
The Java Data Objects (JDO) is another standard for accessing persistent data in databases, using plain old Java objects (POJO) to represent the object model. Unlike Java Persistence API (JPA ... with both relational and object databases. JDO is supported by many object databases, including ObjectDB