Fatal error: Call to undefined method CI_DB_mysql_driver::group_start() [closed]

I developing codeigniter php web application. There are I got error like this:

Fatal error: Call to undefined method CI_DB_mysql_driver::group_start() in C:\wamp\www\ci_sock\application\models\customer_m.php on line 31

How to solve this. There are my PHP code below:

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++;
    }

There are 31 line $this->db->group_start(); like this.

Please help me solve this.