Menampilkan data user login seperti nama setelah log in

Bagaimana cara menampilkan nama pengguna setelah log in, mohon pencerahannya

Controlernya

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Welcome extends CI_Controller {

	/**
	 * Index Page for this controller.
	 *
	 * Maps to the following URL
	 * 		http://example.com/index.php/welcome
	 *	- or -
	 * 		http://example.com/index.php/welcome/index
	 *	- or -
	 * Since this controller is set as the default controller in
	 * config/routes.php, it's displayed at http://example.com/
	 *
	 * So any other public methods not prefixed with an underscore will
	 * map to /index.php/welcome/<method_name>
	 * @see https://codeigniter.com/user_guide/general/urls.html
	 */
	public function index()
	{
		$this->load->view('login');
	}


	function auth(){
		$user=htmlspecialchars($this->input->post('user',TRUE),ENT_QUOTES);
		$pass=htmlspecialchars($this->input->post('pass',TRUE),ENT_QUOTES);

		$cek_admin=$this->center_model->auth_admin($user,$pass);
		if($cek_admin->num_rows()>0){//jika login sebagai admin
			$data=$cek_admin->row_array();
        	$this->session->set_userdata('masuk',TRUE);
		    $this->session->set_userdata('akses','1');
		    $this->session->set_userdata('ses_id',$data['uid']);
		    $this->session->set_userdata('ses_nama',$data['nama_lengkap']);
			redirect('page');

		}else{ //jika login sebagai guru
		      $cek_guru=$this->center_model->auth_guru($user,$pass);
		      if($cek_guru->num_rows()>0){
			  	    $data=$cek_guru->row_array();
			  	    $this->session->set_userdata('masuk',TRUE);
			  	    $this->session->set_userdata('akses','2');
			  	    $this->session->set_userdata('ses_id',$data['nip']);
			  	    $this->session->set_userdata('ses_nama',$data['nama_guru']);
			  	    redirect('page');

        }else{ //jika login sebagai siswa
				$cek_siswa=$this->center_model->auth_siswa($user,$pass);
				if($cek_siswa->num_rows() > 0){
						$data=$cek_siswa->row_array();
        				$this->session->set_userdata('masuk',TRUE);
						$this->session->set_userdata('akses','3');
						$this->session->set_userdata('ses_id',$data['nis']);
						$this->session->set_userdata('ses_nama',$data['nama_siswa']);
						redirect('page');
					}else{  // jika username dan password tidak ditemukan atau salah
						$url=base_url();
						echo $this->session->set_flashdata('msg','<script>window.alert("Maaf, Anda Tidak Memiliki akses");
                                  window.location=("index.php?view=login")</script>');
						redirect($url);
					}
        }

    }
}

    function logout(){
        $this->session->sess_destroy();
        $url=base_url('');
        redirect($url);
    }
}

Modelnya

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

	class Center_model extends CI_Model {
		//cek username dan password admin
		function auth_admin($user,$pass){
			$query=$this->db->query("SELECT * FROM user WHERE username='$user' AND password=MD5('$pass') LIMIT 1");
			return $query;
		}

		//cek username dan password guru
		function auth_guru($user,$pass){
			$query=$this->db->query("SELECT * FROM guru WHERE nip='$user' AND password=MD5('$pass') LIMIT 1");
			return $query;
		}

		//cek username dan password siswa
		function auth_siswa($user,$pass){
			$query=$this->db->query("SELECT * FROM siswa WHERE nis='$user' AND password=MD5('$pass')LIMIT 1");
			return $query;
		}

	}