codeigniter update particular database row - codeigniter

Question

I'm trying to setup my codeigniter install to allow me to update my database. I have managed to do this using :
function updateValues(){
$this->load->model("get_db");
$newrow = array(
array(
"id" => "3",
"name" => "bruce"
),
array(
"id" => "4",
"name" => "billybob"
)
);
$this->get_db->update2($newrow);
echo "update successful" ;
}
This works and updates rows 3 and 4. I now need to update a single row based on my active user ID. I've tried several lines of code found in many different places via google. Code such as:
echo $this->db->insert_id()
All this does is return a '0'.
So my question is how to I echo or return the current active users ID stored in the database.
I'm pretty sure I've missed something basic as I'm new to codeigniter. Any help would be greatly appreciated.
Thanks
Tim

Answer 1

Simplest way to do this is store the userId in the session when they log in, then you can just retrieve the session variable any time you need it.
Login routine
$this->db->where('userName',$userName);
$this->db->where('password',$password);
$data = $this->db->get('users');
if($data->num_rows() ==1)
{
$userData = $data->result();
$this->session->set_userdata('userId',$userData->userId);
}
Then any time you need it you just recall that userId
$userId = $this->session->userdata('userId');
$newrow = array(
'id'=>$userId,
'name'='Cornelius'
);