10 | DELETE Queries in JPA/JPQL. For example, the EntityManager may not be aware that a cached entity object in its persistence ... of subclasses) from the database. For example, the following three equivalent queries delete all the Country ... . A WHERE clause, which is essential for removing selected entity objects, is supported. For example |
10 | WHERE clause (JPQL / Criteria API) them to the SELECT clause. For example, the following query retrieves all the countries with population size ... WHERE content if any). For example, the following JPQL query: SELECT c FROM Country c WHERE c ... if any): For example, the following JPQL query: SELECT c FROM Country WHERE c.population > :p AND c |
10 | CRUD Database Operations with JPA) require an active transaction. In the example above, every Point object is first constructed as ... see another example of a query that returns a single result: Query q2 = em.createQuery("SELECT AVG(p.x) FROM ... () + 100); // update entity } } em.getTransaction().commit(); In the above example |
10 | Deleting JPA Entity Objects=CascadeType.REMOVE) private Address address; : } In the example above, the Employee ... . The difference between the two settings is in the response to disconnecting a relationship. For example ... objects. Orphan removal can also be set for collection and map fields. For example: @Entity class |
10 | Running JPA Queries collection. For example, a result collection of a parameterized type can be iterated easily using ... might fail, depending on the database content. For example, the following query is expected to return ... are executed using the executeUpdate method. For example, the following query deletes |
10 | Criteria Query Selection and Results: See the SELECT in Criteria Queries section for more details and examples. ORDER BY Clause Elements Elements in ... instance (respectively). See the ORDER BY in Criteria Queries section for more details and examples ... and examples. These interfaces are defined outside the javax.persistence.criteria package |
10 | Shared (L2) Entity Cache except classes that are specified as Cacheable explicitly. For example: @Cacheable // or ... that are specified as non Cacheable explicitly. For example: @Cacheable(false) @Entity public class ... can also be overridden for a specific retrieval operation. For example: em.find(MyEntity2.class |
10 | Comparison in JPQL and Criteria API to <>. When at least one of the two operands is NULL, == and != implement the ordinary Java logic, in which, for example, null == null ... detailed above. Therefore, for example, a double value can be compared to a BigInteger instance ... for building these expressions, as shown in the following examples: // Create String path |
10 | Online Backup that subdirectory with the name of the original database file. For example, backing up a test.odb ... , relative to the ObjectDB home directory on the server side. For example, in client-server mode ... that represents the backup run. This thread can be used, for example, for waiting until the backup |
1 | [ODB1] Chapter 5 - JDO Connections instances are usually obtained for short term use (for example, per web request in a web application ... database (for example, a personal organizer). In multi-user applications (using client server mode ... that uses JDO is not wrapped by a try-catch block (unlike code working with files and I/O, for example, in |
