Use EJB query

The EJB query language is used to specify a query over container-managed entity beans. The language is similar to SQL. An EJB query is independent of the bean's mapping to a persistent store.

An EJB query can be used in three situations...

• To define a finder method of an EJB entity bean.

• To define a select method of an EJB entity bean.

• To dynamically specify a query using the executeQuery() dynamic API.

Finder and select queries are specified in the bean's deployment descriptor using the <ejb-ql> tag. Queries specified in the deployment descriptor are compiled into SQL during deployment. Dynamic queries require the interface provided by WAS Enterprise.

WebSphere's EJB query language is compliant with the EJB QL defined in Sun's EJB 2.0 specification and has additional capabilities as listed in the topic Comparison of EJB 2.0 specification and WebSphere Query Language.

In your WebSphere application, you can define an EJB query in the following ways...

• Application Assembly Tool. When assembling an EJB 2.0 entity bean, specify the <ejb-ql> tag for the finder() or select() method.

• WebSphere Studio Application Developer. When defining an entity bean, specify the <ejb-ql> tag for the finder or select method.

• Dynamic query service. Add the executeQuery() method to your application. The dynamic query API is provided as an Enterprise Extension to WebSphere Application Server.

Before using EJB query, familiarize yourself with query language concepts, starting with the topic, EJB Query Language.

 Usage scenarioExample: EJB queries

 

See Also

EJB query language

 

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