Dynamic table name in join query alias in Laravel 5

How to alias a table name in Laravel 5?

$data['recent_reviews'] = $reviews_table_name::where('source', 'LIKE', '%YELP%')->orderby('reviews_'.$l_state.'.id', 'desc')
    ->leftJoin($res_tbl_name, 'reviews_'.$l_state.'.restaurant_id', '=', $res_tbl_name.'.id')
    ->take(6)
    ->get();

Actually i need the table name alias like below.

$res_tbl_name AS r

Thanks.

via Chebli Mohamed