Occurrence class:
-------------------------------
<class name="Occurrence" table="occurrence" mutable="false">
        <id name="id">
            <generator class="native"/>
        </id>
        <property name="startFrame"/>
        <property name="channelPatternId"/>
        ...
</class>

ChannelPattern class:
----------------------------------
<class name="ChannelPattern" table="channel_pattern">
        <id name="id">
            <generator class="assigned"/>
        </id>
        <many-to-one name="pattern" class="Pattern" lazy="proxy" fetch="select" not-null="false"/>
        <many-to-one name="signature" class="Signature" lazy="proxy" fetch="select" not-null="false"/>
        ...
    </class>

String queryStr = "SELECT DATE(startFrame), COUNT(occ.id) FROM Occurrence occ, ChannelPattern cp " +
                "WHERE cp.id=occ.channelPatternId " +
            "AND (cp.pattern.id='id1' OR  cp.signature.id='sig1')  GROUP BY DATE(startFrame)";
              
Query query2 = this.getHibernateTemplate().getSessionFactory().getCurrentSession().createQuery(queryStr);