Codeigniter Query

i have problem to saving data

this is my Model
i use Sql Server Database

  function UpdateEdit($data)
  {

     $this->db->trans_start();
     $sql = " update [do] set customer='" . $data['Customer'] . "', tgl='" . $data['Tgl'] . "', Notes='" . $data['Notes'] . "', Total=" . $data['Total']
          . " where doid='" . $data['Doid'] . "'";    
     print_r($sql);

      $head =  $this->db->query($sql);

     $this->db->delete("from DoDtl where Doid='" . $Doid . "'");

     $this->db->query($data['Detail']);
     $this->db->trans_complete();
     return TRUE;
  }