php - Codeigniter Session Sets 2nd time during login -

<?php    class login_model extends ci_model {    public function login() {         $username = $_post['uname'];         $password = $_post['pw'];         $query = $this->db->get_where('test_logins', array('name' => $username, 'password' => $password));         $count = $query->num_rows() > 0;         if ($count == 1) {             foreach ($query->result_array() $row)             {                  $exam_id=$row['id'];             }             $query2 = $this->db->get_where('candidates', array('email' =>$_post['email']));             $count2=$query2->num_rows();             //echo($count2);             if($count2==1){                  foreach ($query2->result_array() $row2)                 {                  $candidate_id=$row2['id'];                  $part1=$row2['part1'];                  $part2=$row2['part2'];                  $part3=$row2['part3'];                  $part4=$row2['part4'];                 }                 //set session                 $newdata1 = array(                                     'username' => $username,                                     'exam_id'=> $exam_id,                                     'candidate_id'=> $candidate_id,                                     'logged_in' => true                                  );                 $this->session->set_userdata($newdata1);                 if(empty($part1)){                     return 'part1';                 }else if(empty($part2)){                     return 'part2';                 }else if(empty($part3)){                     return 'part3';                 }else if(empty($part4)){                     return 'part4';                 }             }else{             $data = array(                                'name' => $_post['name'],                                'email' => $_post['email'],                                'exam_id' => $exam_id,                                'contact' => $_post['mobile'],                          );                                $this->db->insert('candidates', $data);                                $candidate_id=$this->db->insert_id();             $newdata = array(                 'username' => $username,                 'exam_id'=> $exam_id,                 'candidate_id'=> $candidate_id,                 'logged_in' => true             );             $this->session->set_userdata($newdata);             return 'part1';             }//else insert candidate          }else {             return false;         }      }   } ?> 

checking if login id , password correct. if yes checking if user registered exam or not, if registered user creating session checking part of exam remaining , redirecting parts controller, if not registered creating record , creating session redirecting 1st part of exam, session null on 1st attempt , gets set 2nd attempt.

the code mentioned in question having flaws write clean , in codeigniter way here plz try , let me know then. unable put whole code comment write answer :)

<?php  class login_model extends ci_model {      public function login()      {         $username = $this->input->post['uname'];         $password = $this->input->post['pw'];         $exam_id  = 0;         $candidate_id = 0;          $query = $this->db->get_where('test_logins', array(             'name' => $username,              'password' => $password         ));          if ($query->num_rows() > 0)          {             $row = $query->row();             if (isset($row))              {                 $exam_id = $row->id;             }              $query2 = $this->db->get_where('candidates', array(                 'email' => $this->input->post('email')             ));              if ($query2->num_rows() > 0)             {                 $row2 = $query2->row();                 if (isset($row2))                  {                     $candidate_id = $row2->id;                     $part1        = $row2->part1;                     $part2        = $row2->part2;                     $part3        = $row2->part3;                     $part4        = $row2->part4;                 }                  if(empty($part1)) { return 'part1'; }                  else if(empty($part2)) { return 'part2'; }                  else if(empty($part3)) { return 'part3'; }                  else if(empty($part4)) { return 'part4'; }             }             else             {                 $this->db->insert('candidates', array(                     'name' => $this->input->post('name'),                     'email' => $this->input->post('email'),                     'exam_id' => $exam_id,                     'contact' => $this->input->post('mobile')                 ));                  return 'part1';             }              $this->session->set_userdata(array(                 'username' => $username,                 'exam_id'=> $exam_id,                 'candidate_id'=> $candidate_id,                 'logged_in' => true             ));          } else {             return false;         }     } }