trasaction_ci

			$this->db->trans_off();
            $this->db->trans_start();
            $data_update=array('total_tagihan' => 'total_tagihan+'.$tagihan);
            $this->db->update('pembayaran_mhs',$data_update,$npm);
            $this->db->trans_complete();
            if ($this->db->trans_status() === FALSE){
                // generate an error... or use the log_message() function to log your error
                $data=array(
                    'status_transaction' => $this->db->trans_status(),
                    'status'             => 'Error!'
                );
            }else{
                $data=array(
                    'status_transaction' => $this->db->trans_status(),
                    'status'             => 'Succes!'
                );
            }