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Deleting JPA Entity Objects

method or implicitly as a result of a cascade operation. Explicit Remove In order to delete an object ... if the argument is not an instance of an entity class or if it is a detached entity ... with CascadeType.REMOVE (or CascadeType.ALL, which includes REMOVE) indicates that remove operations

Posting Sample Code

To demonstrate a technical question or an issue - you may have to provide a complete runnable sample program. If an unexpected exception (e.g. NullPointerException or ClassCastException) is thrown by ... should have a no-arg public or protected constructor, An entity class must be a top level class, The project does

ObjectDB Object Database Features

Requirements Windows, Linux, Unix, Mac OS, and most other OS with Java support. Java 8 or higher Tested ... a proprietary API - any user with some experience with Hibernate, TopLink, EclipseLink, OpenJPA, JPOX or ... - multiple @Id fields or a @EmbeddedId field. Primary Key Data Types Primitives (boolean, byte, short

JPA Criteria API Queries

the EntityManagerFactory's getCriteriaBuilder method or by the EntityManager's getCriteriaBuilder method (both methods ... ); List<Country> results = query.getResultList(); The setParameter method takes a Parameter (or a ParameterExpression) instance as the first argument instead of a name or a position (which are used


must be eliminated from the query result or whether they must be retained Returns: the modified ... whether duplicate results must be eliminated from the query result or whether they must be retained Returns ... to the restriction(s) over the grouping items, or null if no restrictions have been specified. Return


/JPQL queries in Chapter 4 of the ObjectDB/JPA manual. int executeUpdate() Execute an update or delete statement. Execute an update or delete statement. Returns: the number of entities updated or deleted Throws: IllegalStateException - if called for a Java Persistence query language SELECT statement or


restriction predicates. A conjunction of zero predicates is true. Parameters: restrictions - zero or ... compound selection Throws: IllegalArgumentException - if an argument is a tuple- or array-valued ... selection item Throws: IllegalArgumentException - if an argument is a tuple- or array-valued selection

SELECT clause (JPQL / Criteria API)

projection. The field values are extracted from (or projected out of) entity objects to form the query ... efficiently. They are less productive with operations that update or delete entity objects, in ... to using select with one of the factory methods (array, tuple or construct) as demonstrated

Step 2: Entity Class and Persistence Unit

) and selecting New > Entity Class... (or New > Other... > Persistence > Entity Class and clicking ... a text editor (by right clicking and selecting Edit or by double click and then moving to the Source or XML tab in the editor window). Use copy and paste to replace the default content


the PersistenceManagerFactory (recommended) or by construction. Since: JDO 1.0 void ... a PersistenceManager might release it to the pool of available PersistenceManagers, or might be garbage collected ... JDOUserException if the instance is transient or is managed by another PersistenceManager. Parameters: pc

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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