Enterprise JavaBeans Query Language - The J2EE 1.4 Tutorial

Enterprise JavaBeans
Query Language

The Enterprise JavaBeans Query Language (EJB QL) defines the queries for the finder and select methods of an entity bean that uses container-managed persistence. A subset of SQL92, EJB QL has extensions that allow navigation over the relationships defined in an entity bean's abstract schema. The scope of an EJB QL query spans the abstract schemas of related entity beans that are packaged in the same EJB JAR file.

You define EJB QL queries in the deployment descriptor of the entity bean. Typically, a tool will translate these queries into the target language of the underlying data store. Because of this translation, entity beans with container-managed persistence are portable; their code is not tied to a specific type of data store.

This chapter relies on the material presented in earlier chapters. For conceptual information, see the section Container-Managed Persistence. For code examples, see Chapter 27.

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