protected function _quoteComparison(FieldInterface $expression)
    {
        $field = $expression->getField();
        if (is_string($field)) {
            $expression->setField($this->_driver->quoteIdentifier($field));
        } elseif (is_array($field)) {
            $quoted = [];
            foreach ($field as $f) {
                $quoted[] = $this->_driver->quoteIdentifier($f);
            }
            $expression->setField($quoted);
        } elseif ($field instanceof ExpressionInterface) {
            $this->quoteExpression($field);
        }
    }