请问这个criteria 该如何写 [ 新手入门 ]

public function search()
{
    // Warning: Please modify the following code to remove attributes that
    // should not be searched.

    $criteria=new CDbCriteria;

    $criteria->compare('id',$this->id);
    $criteria->compare('name',$this->name,true);
		    
    $criteria->join='RIGHT JOIN city ON city.name=city  and city.username = 当前登录用户';

    return new CActiveDataProvider($this, array(
        'criteria'=>$criteria,
    ));
}

这里的 $criteria->join='RIGHT JOIN city ON city.name=city and city.username = 当前登录用户';

当前登录用户 可能是demo/demo ，也可能是 admin/admin，我打算再增加一些用户，当前登录用户' 该如何填写。