If you use Hibernate 3.6 with HSQLDB 2.0.1 or later, you can use a connection property sql.syntax_ora=true on your connection URL. This enables the DUAL table together with some other Oracle specific syntax.

You probably need a few more connection properties for behaviour that is not covered by the main property. See: http://hsqldb.org/doc/2.0/guide/management-chapt.html#mtc_compatibility_oracle