join

Controller:
public function ajax_list()
{
    $list = $this->Foto_model->get_datatables();
    $data = array();
    $no = $_POST['start'];

    foreach ($list as $data_foto) {
      $no++;
      $row = array();
      $row[] = '<p style="text-align: center">'.$no.'</p>';
      $row[] = '<p style="text-align: left">'.$data_foto->judul_foto.'</p>';
      $row[] = '<p style="text-align: left">'.$data_foto->judul_album.'</p>';
      $row[] = '<p style="text-align: center"><img src="'.base_url('assets/images/foto/').$data_foto->ufile.$data_foto->ufile_type.'" width="100px"></p>';
      $row[] = "
      <p style='text-align: center'>
        <a class='btn btn-sm btn-warning' href='".base_url('admin/foto/update/').$data_foto->id_foto."' title='Edit'><i class='fa fa-pencil'></i> EDIT</a>
      </p>
      <p style='text-align: center'>
        <a class='btn btn-sm btn-danger' href='".base_url('admin/foto/delete/').$data_foto->id_foto."', onClick=\"return confirm('Apakah Anda yakin?');\"><i class='glyphicon glyphicon-trash'></i> HAPUS</a>
      </p>";

      $data[] = $row;
    }

    $output = array(
              "draw" => $_POST['draw'],
              "recordsTotal" => $this->Foto_model->count_all(),
              "recordsFiltered" => $this->Foto_model->count_filtered(),
              "data" => $data
              );
    //output to json format
    echo json_encode($output);
}

Model:
public function get_datatables()
  {
    $this->_get_datatables_query();
    if($_POST['length'] != -1)
    $this->db->limit($_POST['length'], $_POST['start']);
    $this->db->select('id_foto, judul_foto, judul_album, foto.userfile as ufile,foto.userfile_type as ufile_type');
    $this->db->join('album ', 'album.id_album = foto.id_foto','left');

    $query = $this->db->get();

    return $query->result();
  }

View:
<section class="content">
    <div class="box box-primary">
      <div class="box-body table-responsive padding">
        <a href="<?php echo $action_add ?>">
          <button class="btn btn-success"><i class="fa fa-plus"></i> Tambah <?php echo $title ?> Baru</button>
        </a>
        <button class="btn btn-grey" onclick="reload_table()">
          <i class="glyphicon glyphicon-refresh"></i> Refresh
        </button>

        <h4 align="center"><?php echo $this->session->userdata('message') <> '' ? $this->session->userdata('message') : ''; ?></h4>

        <hr/>
        <table id="table" class="table table-striped table-bordered">
          <thead>
            <tr>
              <th style="text-align: center">No.</th>
              <th style="text-align: center">Judul Foto</th>
              <th style="text-align: center">Album</th>
              <th style="text-align: center">Foto</th>

              <th style="text-align: center">Aksi</th>
            </tr>
          </thead>
          <tbody></tbody>
        </table>
      </div>
      </div>
  </section>

<!-- DATA TABLES SCRIPT -->
<script src="<?php echo base_url('assets/plugins/datatables/jquery.dataTables.min.js') ?>" type="text/javascript"></script>
<script src="<?php echo base_url('assets/plugins/datatables/dataTables.bootstrap.min.js') ?>" type="text/javascript"></script>
<script type="text/javascript">
var table;
$(document).ready(function() {
  table = $('#table').DataTable({
    "processing": true, //Feature control the processing indicator.
    "serverSide": true, //Feature control DataTables' server-side processing mode.
    "bPaginate": true,
    "bLengthChange": true,
    "bFilter": true,
    "bSort": true,
    "bInfo": true,
    "bAutoWidth": false,
    "aaSorting": [[0,'desc']],
    "lengthMenu": [[10, 25, 50, 100, 500, 1000, -1], [10, 25, 50, 100, 500, 1000, "Semua"]],

    // Load data for the table's content from an Ajax source
    "ajax": {
        "url": "<?php echo site_url('admin/foto/ajax_list')?>",
        "type": "POST"
    },

    //Set column definition initialisation properties.
    "columnDefs": [
    {
      "targets": [ -1 ], //last column
    },
    ],
  });
});

function reload_table(){
  table.ajax.reload(null,false); //reload datatable ajax
}
</script>