Broadleaf Commerce Discussion Forums

I want to handle multiple table queries.So, can please suggest me an approach on the broadleaf.
http://forum.broadleafcommerce.org/viewtopic.php?f=15&t=1576
http://grepcode.com/file/repo1.maven.org/maven2/org.broadleafcommerce/broadleaf-framework/2.4.1-GA/config/bc/jpa/domain/Content.orm.xml/