Joomla模块外部数据库查询

I have a module built in Joomla to fetch data from an external database. I want to display the table data in my Joomla page and although the module loads up fine, no data is displayed.

Here is what I have in my helper.php page.

<?php

defined('_JEXEC') or die('');

class ModChannelLineupsHelper
{

    static function doDataFetch ($param) {
        // ...

        // ...

$option = array(); //prevent problems
$option['driver']   = 'mysql';            // Database driver name
$option['host']     = 'localhost';    // 
$option['user']     = 'usenamehere';       // User for database authentication
$option['password'] = 'passhere';   // Password for database authentication
$option['database'] = 'cars';      // Database name

$db = JDatabaseDriver::getInstance( $option );

 // Get a db connection and create a query object.

 $query = $db->getQuery(true)


->select('*')
->from($db->qn('zcars'))
->where($db-qn('Make_ID') . ' = 13')
->order($db->qn('Model') . ' ASC');

$db->setQuery($query);
$rows = $db->loadObjectList();
foreach ( $row as $row ) {
    echo $row->Model;
}
    }
}

Do i need to do something special in Joomla to display the information?

Thanks