I can not fetch information from a MS SQL database through ODBC and with Codeigniter query Builder

Question

Good,

I am trying to create a login page with Codeigniter.

It turns out, to validate the entered data, I need to fetch information from a MS SQL database through ODBC. When using the Codeigniter query Builder, I get the following error:

Call to Undefined method Ci_db_odbc_driver::select()

What is the reason for this to happen?

Model

class Utilizador_model extends CI_Model {

public function login($username,$password){
    $this->db->select('*');
    $this->db->from('utilizadores');
    $this->db->where('username', $username);
    $this->db->where('password', $password);
    $q = $this->db->get();

    if ($q->num_rows() > 0) {
     return $q->result_array();
    }else{
        return false;
    }
}