31.6.4. JBossQL

JBossQL is a superset of EJB-QL that is designed to address some of the inadequacies of EJB-QL. In addition to a more flexible syntax, new functions, key words, and clauses have been added to JBossQL. At the time of this writing, JBossQL includes support for an ORDER BY, OFFSET and LIMIT clauses, parameters in the IN and LIKE operators, the COUNT, MAX, MIN, AVG, SUM, UCASE and LCASE functions. Queries can also include functions in the SELECT clause for select methods.

JBossQL is declared in the jbosscmp-jdbc.xml file with a jboss-ql element containing the JBossQL query. The following example provides an example JBossQL declaration.

<jbosscmp-jdbc>
    <enterprise-beans>
        <entity>
            <ejb-name>GangsterEJB</ejb-name>
            <query>
                <query-method>
                    <method-name>findBadDudes_jbossql</method-name>
                    <method-params>
                        <method-param>int</method-param>
                    </method-params>
                </query-method>
                <jboss-ql>SELECT OBJECT(g) FROM gangster g WHERE g.badness > ?1 ORDER BY g.badness DESC</jboss-ql>
            </query>
        </entity>
    </enterprise-beans>
</jbosscmp-jdbc>

<jbosscmp-jdbc>
    <enterprise-beans>
        <entity>
            <ejb-name>GangsterEJB</ejb-name>
            <query>
                <query-method>
                    <method-name>findBadDudes_jbossql</method-name>
                    <method-params>
                        <method-param>int</method-param>
                    </method-params>
                </query-method>
                <jboss-ql>SELECT OBJECT(g) FROM gangster g WHERE g.badness > ?1 ORDER BY g.badness DESC</jboss-ql>
            </query>
        </entity>
    </enterprise-beans>
</jbosscmp-jdbc>

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The corresponding generated SQL is straightforward.

SELECT t0_g.id
    FROM gangster t0_g
    WHERE t0_g.badness > ?
    ORDER BY t0_g.badness DESC

SELECT t0_g.id
    FROM gangster t0_g
    WHERE t0_g.badness > ?
    ORDER BY t0_g.badness DESC

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Another capability of JBossQL is the ability to retrieve finder results in blocks using the LIMIT and OFFSET functions. For example, to iterate through the large number of jobs performed, the following findManyJobs_jbossql finder may be defined.

<jbosscmp-jdbc>
    <enterprise-beans>
        <entity>
            <ejb-name>GangsterEJB</ejb-name>
            <query>
                <query-method>
                    <method-name>findManyJobs_jbossql</method-name>
                    <method-params>
                        <method-param>int</method-param>
                    </method-params>
                    <method-params>
                        <method-param>int</method-param>
                    </method-params>
                </query-method>
                <jboss-ql>SELECT OBJECT(j) FROM jobs j OFFSET ?1 LIMIT ?2</jboss-ql>
            </query>
        </entity>
    </enterprise-beans>
</jbosscmp-jdbc>

<jbosscmp-jdbc>
    <enterprise-beans>
        <entity>
            <ejb-name>GangsterEJB</ejb-name>
            <query>
                <query-method>
                    <method-name>findManyJobs_jbossql</method-name>
                    <method-params>
                        <method-param>int</method-param>
                    </method-params>
                    <method-params>
                        <method-param>int</method-param>
                    </method-params>
                </query-method>
                <jboss-ql>SELECT OBJECT(j) FROM jobs j OFFSET ?1 LIMIT ?2</jboss-ql>
            </query>
        </entity>
    </enterprise-beans>
</jbosscmp-jdbc>

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31.6.4. JBossQL

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