<table id="table" class="table table-striped table-bordered" cellspacing="0" width="100%">
        <thead>
            <tr>
                <th bgcolor="#BDBDBD">Rotina</th>
                <th bgcolor="#BDBDBD">Descricao</th>
                <th bgcolor="#BDBDBD">Previsto</th>
                <th bgcolor="#BDBDBD">Realizado</th>
            </tr>
        </thead>
        <tbody>
        </tbody>

        <tfoot>
        <tr>
            <th bgcolor="#BDBDBD"></th>
            <th bgcolor="#BDBDBD"></th>
            <th bgcolor="#BDBDBD"></th>
            <th bgcolor="#BDBDBD"></th>
        </tr>
        </tfoot>
    </table>

$(document).ready(function() {

//datatables
table = $('#table').DataTable({

    "processing": true, //Feature control the processing indicator.
    "serverSide": true, //Feature control DataTables' server-side processing mode.
    "order": [], //Initial no order.

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

    //Set column definition initialisation properties.
    "columnDefs": [
    {
        "targets": [ -1 ], //last column
        "orderable": false, //set not orderable
    },
    ],

});
});

public function ajax_list()
{
    $list = $this->projeto->get_datatables();
    $data = array();
    $no = $_POST['start'];
    foreach ($list as $projeto) {
        $no++;
        $row = array();
        $row[] = $projeto->rotina;
        $row[] = $projeto->descricao;
        $row[] = $projeto->previsto;
        $row[] = $projeto->realizado;

        $data[] = $row;
    }

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


private function _get_datatables_query()
{

    $this->db->from($this->table);

    $i = 0;

    foreach ($this->column_search as $item) // loop column
    {
        if($_POST['search']['value']) // if datatable send POST for search
        {

            if($i===0) // first loop
            {
                $this->db->group_start(); // open bracket. query Where with OR clause better with bracket. because maybe can combine with other WHERE with AND.
                $this->db->like($item, $_POST['search']['value']);
            }
            else
            {
                $this->db->or_like($item, $_POST['search']['value']);
            }

            if(count($this->column_search) - 1 == $i) //last loop
                $this->db->group_end(); //close bracket
        }
        $i++;
    }

    if(isset($_POST['order'])) // here order processing
    {
        $this->db->order_by($this->column_order[$_POST['order']['0']['column']], $_POST['order']['0']['dir']);
    }
    else if(isset($this->order))
    {
        $order = $this->order;
        $this->db->order_by(key($order), $order[key($order)]);
    }
}

function get_datatables()
{
    $this->_get_datatables_query();
    if($_POST['length'] != -1)
    $this->db->limit($_POST['length'], $_POST['start']);
    $query = $this->db->get();
    return $query->result();
}