Yii distinct 唯一查询

$criteria = new CDbCriteria;
$criteria->alias = 't';  //table t，默认select='*';
//一些public vars
$criteria->select = 'id,parentid,name'; //代表了要查询的字段，默认select='*';
$criteria->join = 'xxx'; //连接表
$criteria->with = 'xxx'; //调用relations   $criteria->with = array('accounts','varchar');
$criteria->with  = array('teacher'=>
    array('select'=>'username,company_id',
     'order'=>'teacher.username ASC')
);
$criteria->limit = 10;    //取1条数据，如果小于0，则不作处理
$criteria->offset = 1;   //两条合并起来，则表示 limit 10 offset 1,或者代表了。limit 1,10
$criteria->order = 'xxx DESC,XXX ASC' ;//排序条件
$criteria->group = 'group 条件';
$criteria->having = 'having 条件 ';
$criteria->distinct = FALSE; //是否唯一查询
Article::model()->findAll($criteria);