protected function addClassTable()
    {
        $table = $this->createTable($this->options['class_table_name']);
        $table->addColumn('id', 'integer', array('unsigned' => true, 'autoincrement' => true));
        $table->addColumn('class_type', 'string', array('length' => 200));
        $table->setPrimaryKey(array('id'));
        $table->addUniqueIndex(array('class_type'));
    }