How Can I use model criteria not use namespace?

There's my code:

$data = self::query() ->columns('Raise\Basic\Models\Product.*,c.catname') ->leftJoin('Raise\Basic\Models\Category','c.catid=Raise\Basic\Models\Product.cat_id','c') ->orderBy('Raise\Basic\Models\Product.sort ASC') ->execute(); it's work;

when i not write namespace like this

$data = self::query() ->columns('Product.*,c.catname') ->leftJoin('Category','c.catid=Product.cat_id','c') ->orderBy('Product.sort ASC') ->execute();

it's not work!

this is my model code:

namespace Raise\Basic\Models;

class Product extends BaseModel {

/**
 *
 * @var integer
 */
public $pr_id;

/**
 *
 * @var string
 */
public $pr_name;

/**
 *
 * @var integer
 */
public $cat_id;

/**
 *
 * @var double
 */
public $min_price;

/**
 *
 * @var double
 */
public $max_price;

/**
 *
 * @var double
 */
public $max_deduct_rate;

/**
 *
 * @var double
 */
public $max_deduct_price;

/**
 *
 * @var integer
 */
public $sort;

/**
 *
 * @var integer
 */
public $add_time;


public static  function loadList()
{
  $data = self::query()
      ->columns('Raise\Basic\Models\Product.*,c.cat_name')
      ->leftJoin('Raise\Basic\Models\Category','c.cat_id=Raise\Basic\Models\Product.cat_id','c')
      ->orderBy('Raise\Basic\Models1\Product.sort ASC')
      ->execute();


  //return self::getPages($data,20);
}

public function getSource()
{
  return $this->prefix.'product';
}

public static function model($className = __CLASS__) {
  return parent::model($className);
}

}

Try this;

  $data = self::query() ->columns('Product.*,c.cat_name') ->leftJoin('Category','c.cat_id=Product.cat_id','c') ->orderBy('Product.sort ASC');

     $this->getDI()->get('db')->prepare($data)->execute();