Multiple Databases and Multiple Domains Follow @yiiframework

'components'=>array(
.........
        'db'=>array(
            'connectionString' => 'mysql:host=localhost;dbname=database1',
            'emulatePrepare' => true,
            'username' => 'root',
            'password' => 'itsasecret',
            'charset' => 'utf8',
        ),
        'db2'=>array(
            'class' => 'CDbConnection',
            'connectionString' => 'mysql:host=localhost;dbname=database2',
            'emulatePrepare' => true,
            'username' => 'root',
            'password' => 'itsasecret',
            'charset' => 'utf8',
        ),
....
),

abstract class AltActiveRecord extends CActiveRecord
{
    const BELONGS_TO='CBelongsToRelation';
    const HAS_ONE='CHasOneRelation';
    const HAS_MANY='CHasManyRelation';
    const MANY_MANY='CManyManyRelation';
    const STAT='CStatRelation';
 
    /**
     * @var CDbConnection the default database connection for all active record classes.
     * By default, this is the 'db' application component.
     * @see getDbConnection
     */
    public static $db;
 
    private static $_models=array();            // class name => model
 
    private $_md;                               // meta data
    private $_new=false;                        // whether this instance is new or not
    private $_attributes=array();               // attribute name => attribute value
    private $_related=array();                  // attribute name => related objects
    private $_c;                                // query criteria (used by finder only)
    private $_pk;                               // old primary key value
 
    /**
     * Returns the database connection used by active record.
     * By default, the "db" application component is used as the database connection.
     * You may override this method if you want to use a different database connection.
     * @return CDbConnection the database connection used by active record.
     */
    public function getDbConnection()
    {
        if(self::$db!==null)
            return self::$db;
        else
        {
 
            // Create CDbConnection and set properties
            self::$db = new CDbConnection();
            foreach(Yii::app()->db2 as $key => $value)
                self::$db->$key = $value;
 
 
        // Uncomment the following lines to prove that you have two database connections
        /*
            CVarDumper::dump(Yii::app()->db);
            echo '<br />';
            CVarDumper::dump(Yii::app()->db2);
            die;
        */
            if(self::$db instanceof CDbConnection)
            {
                self::$db->setActive(true);
                return self::$db;
            }
            else
                throw new CDbException(Yii::t('yii','Active Record requires a "db" CDbConnection application component.'));
        }
    }
}

/**
 * This is the model class for table "pagedata".
 */
class Pagedata extends AltActiveRecord
{
..
// model stuff here
..
}

// change the following paths if necessary
$hostname = $_SERVER['SERVER_NAME'];
$yii=dirname(__FILE__).'/../../framework/yii.php';
 
switch ( strtolower($hostname))
{
case 'example1.com';
case 'www.example1.com';
    $config=dirname(__FILE__).'/protected/config/main.php';
    // database 1
break;
case 'example2.com';
case 'www.example2.com';
    $config=dirname(__FILE__).'/protected/config/main2.php';
    // database 2
break;
 
case 'example3.com';
case 'www.example3.com';
    $config=dirname(__FILE__).'/protected/config/useAnyName.php';
    // database 3 
break;
 
default:
$config=dirname(__FILE__).'/protected/config/main.php';
}
// remove the following lines when in production mode
defined('YII_DEBUG') or define('YII_DEBUG',true);
defined('YII_TRACE_LEVEL') or define('YII_TRACE_LEVEL',3);
 
require_once($yii);
Yii::createWebApplication($config)->run();

// application-level parameters that can be accessed
    // using Yii::app()->params['paramName']
    'params'=>array(
        // this is used in contact page
        'adminEmail'=>'admin@example1.com',
        'googleCode'=>'UA-2****8-11',
        'juitheme'=>'dark-hive',
        'cssfile'=>'cwdi'
    ),

<link rel="stylesheet" type="text/css" href="<?php echo Yii::app()->request->baseUrl; ?>/css/<?php echo Yii::app()->params->cssfile; ?>.css" />