$data = array(
               'title' => $title,
               'name' => $name,
               'date' => $date
            );

$this->db->where('id', $id);
$this->db->update('mytable', $data); 

// 生成:  UPDATE mytable SET title = '{$title}', name = '{$name}', date = '{$date}'  WHERE id = $id


/*
    class Myclass {
        var $title = 'My Title';
        var $content = 'My Content';
        var $date = 'My Date';
    }
*/

$object = new Myclass;

$this->db->where('id', $id);
$this->db->update('mytable', $object); 

// 生成:  UPDATE mytable  SET title = '{$title}', name = '{$name}', date = '{$date}'  WHERE id = $id