About JDOQL Queries

The Enterprise JavaBeans Specification, v1.1 spec does not specify the format of the finder method description. The Application Server uses an extension of Java Data Objects Query Language (JDOQL) queries to implement finder and selector methods. (For EJB 2.0 and later, the container automatically maps an EJB QL query to JDOQL.) You can specify the following elements of the underlying JDOQL query:

• Filter expression - A Java-like expression that specifies a condition that each object returned by the query must satisfy. Corresponds to the WHERE clause in EJB QL.

• Query parameter declaration - Specifies the name and the type of one or more query input parameters. Follows the syntax for formal parameters in the Java language.

• Query variable declaration - Specifies the name and type of one or more query variables. Follows the syntax for local variables in the Java language. A query filter might use query variables to implement joins.

• Query ordering declaration - Specifies the ordering expression of the query. Corresponds to the ORDER BY clause of EJB QL.

The Application Server specific deployment descriptor (sun-ejb-jar.xml) provides the following elements to store the EJB 1.1 finder method settings:

query-filterquery-paramsquery-variablesquery-ordering

The bean developer uses these elements to construct a query. When the finder method that uses these elements executes, the values of these elements are used to execute a query in the database. The objects from the JDOQL query result set are converted into primary key instances to be returned by the EJB 1.1 ejbFind method.

The JDO specification (see JSR 12) provides a comprehensive description of JDOQL. The following information summarizes the elements used to define EJB 1.1 finders.