Why am I not able to retrieve data - Codeigniter?

I recently added a column called user_cat to a table. I am not able to get this date to display on the webpage. However, I am able to display the data from columns user_id, email_id on the webpage using session variables using below.

$this->session->set_userdata("user_id", $this->session->userdata('loginUser') );

$this->session->set_userdata("user_id", $this->session->userdata('loginEmail') );

I checked the models page to and found the code to be like this.

$this->db->select('user_id,email_id');

&

'loginUser' => $row->user_id,

'loginEmail' => $row->email_id,

which i then changed to:

$this->db->select('user_id,email_id,user_cat');

&

'loginUser' => $row->user_id,
'loginCat'  => $row->   user_cat,
'loginEmail' => $row->email_id,

Now i used the session variable like this:

$this->session->set_userdata("user_id", $this->session->userdata('loginCat') );

This did not work. I need help.