 36 | The following subsections explain how to use JPA for CRUD database operations: |
36 | The syntax of the Java Persistence Query Language (JPQL) is very similar to the syntax of SQL. Having a SQL like syntax in JPA queries is an important advantage because SQL is a very powerful query language and many developers are already familiar with it. The main difference between SQL and JPQL |
36 | The following annotations can mark methods as JPA callback methods: The Lifecycle Events section of the ObjectDB Manual explains how to use all these annotations on callback methods and with listener classes. |
36 | Relationships are persistent fields in persistable classes that reference other entity objects. The four relationship modes are represented by the following annotations: Unlike ORM JPA implementations, ObjectDB does not enforce specifying any of the annotations above. Specifying a relationship |
36 | The following interfaces and enum represent types in the JPA Metamodel API: See the Metamodel Type Interface Hierarchy section for more details and examples. |
36 | setting the ObjectDB configuration or in a JPA portable way, by specifying the cascade-persist XML |
36 | Callback methods are user defined methods that are attached to entity lifecycle events and are invoked automatically by JPA when these events occur. Internal Callback Methods Internal callback methods are methods that are defined within an entity class. For example, the following entity class |
36 | The following interfaces and enum types represent attributes (persistent fields and properties) in the JPA Metamodel API: See the Metamodel Attribute Interface Hierarchy section for more details and examples. |
36 | This section discusses advanced JPA topics: |
36 | To store objects in an ObjectDB database using JPA we need to define an entity class: Open the [New Java Class] dialog box, e.g. by right clicking the project node (in the [Package Explorer] window) and selecting New > Class. Enter tutorial as the package name - use exactly that case sensitive |