help noob with select_sum

[eluser]xxIdroxx[/eluser]
Hello everyone, I'm a beginner with CodeIgniter and I need to select a field to a table and add up all the data I can find.
I tried to do this script but it goes:

Code:

$query = $this->db->get_where($this->session->userdata('universe').'_alleanza_utenti', array('ally_id' => $param5));
     $this->db->select_sum('points');
  foreach ($query->result_array() as $row)
{
    $query1 = $this->db->get_where($this->session->userdata('universe').'_users', array('id' => $row['user_id']));
}
  $row = $query1->row();
  
     echo number_format($row->points);