private function _addFilterComparison($firstObj, $firstProperty, $property, $value)
    {
        if ($firstObj && $firstProperty) {
            $this->_parseComparison(self::COMPARISON_LOGIC_WHERE, $property, $value);
        } else if (!$firstObj && $firstProperty) {
            $this->_parseComparison(self::COMPARISON_LOGIC_OR, $property, $value);
        } else {
            $this->_parseComparison(self::COMPARISON_LOGIC_AND, $property, $value);
        }
    }