Yii: adding custom fields - yii

Question

Is there a simple way of adding custom fields to a model? Say I have a table "user" with 3 fields: id, name and surname. I want this:
$user = User::model()->findByPk(1);
$echo $user->fullName; // echoes name and surname
Please note: I want this custom field to be added via sql, smth like
$c = new CDbCriteria();
$c->select = 'CONCAT("user".name, "user".surname) as fullName';
$user = User::model()->find($c);
Problem is that fullName property is not set.
UPD:
here is the code for a little bit trickier problem -- custom field from another table. This is how it's done:
$model = Application::model();
$model->getMetaData()->columns = array_merge($model->getMetaData()->columns, array('fullName' => 'CONCAT("u".name, "u".surname)'));
$c = new CDbCriteria();
$c->select = 'CONCAT("u".name, "u".surname) as fullName';
$c->join = ' left join "user" "u" on "t".responsible_manager_id = "u".id';
$model->getDbCriteria()->mergeWith($c);
foreach ($model->findAll() as $o) {
echo '<pre>';
print_r($o->fullName);
echo '</pre>';
}

Answer 1

You can add a function to the User class:
public function getFullName() { return $this->name.' '.$this->surname; }
This will return the full name as if it were an attribute from the database. This is much easier than adding a calculated column to the SQL.

Answer 2

In model
public function getMetaData(){
$data = parent::getMetaData();
$data->columns['fullName'] = array('name' => 'fullName');
return $data;
}
Thus not recommended