if (isset($_POST['submit'])) {
     $invoiceId = $_POST['invoiceId'];
     $client = $_POST['Client'];
     $address = $_POST['Address'];
     $Date = $_POST['Date'];
     $suBTotal = $_POST['subTotal'];

     foreach($_POST['data'] as $key => $value) {
             $invoiceItemId = intval($value['invoiceItemId']);
             $itemId = intval($value['ItemId']);
             $item = strip_tags(trim(strval($value['item'])));
             $QTY = intval($value['QTY']);
             $addedQTY = intval($value['addedQTY']);
             $subtractedQty = intval($value['subtractedQty']);
             $Price = is_numeric($value['price']) ? $value['price'] : false;
             $Total = is_numeric($value['total']) ? $value['total'] : false;

             try {

                 $updateInvoice = $db - > prepare(" UPDATE `invoices` SET
                         client = : client,
                         Address = : Address,
                         Date = : Date,
                         subTotal = : subTotal WHERE `invoiceId` = : invoiceId ");

                         $updateInvoice - > bindparam(':client', $client); $updateInvoice - > bindparam(':Address', $address); $updateInvoice - > bindparam(':Date', $Date); $updateInvoice - > bindparam(':subTotal', $suBTotal); $updateInvoice - > bindparam(':invoiceId', $invoiceId);

                         $invoiceUpdate = $updateInvoice - > execute();


                    if ($invoiceItemId === 0) {


                        $insertNewItems = $db - > prepare(" INSERT INTO `invoiceItems`                                                                                  (`invoiceId`,`ItemId`,`Item`,`qty`,`Price`,`Total`)
                            values(: invoiceId, : ItemId, : item, : qty, : Price, : Total)
                            ");

                            $insertNewItems - > execute(array(':invoiceId' => $invoiceId, ':ItemId' => $itemId, ':item' => $item, ':qty' => $QTY, ':Price' => $Price, ':Total' => $Total));

                            $updateItems = $db - > prepare("UPDATE items SET QTY = QTY - :QTY where id= :iId  ");

                            $updateItems - > execute(array(':iId' => $itemId, ':QTY' => $QTY));

                        }
                        elseif($addedQTY > 0) {
                            $updateInvoiceAddedItems = $db - > prepare("UPDATE `invoiceItems` SET
                                qty = qty + : addedQTY,
                                addedQty = addedQty + : addingQTY where id = : Iid ");

                                $updateInvoiceAddedItems - > execute(array(':Iid' => $itemId, ':addedQTY' => $addedQTY, ':addingQTY' => $addedQty));

                                $updateItemsAfterAddition = $db - > prepare("UPDATE items SET QTY = QTY - :addedQTY where id= :iIid");

                                $updateItemsAfterAddition - > execute(array(':iIid' => $ProId, ':addedQTY' => $addedQty));


                            }
                            elseif($subtractedQty > 0) {
                                $updateInvoiceSubtractedItems = $db - > prepare("UPDATE `invoiceItems`  SET
                                    qty = qty - : subtractedQty,
                                    subtractedQty = subtractedQty + : subtractingQty where id = : iiId ");

                                    $sub_invoiceItems - > execute(array(':iiId' => $itemId, ':subtractedQty' => $subtractedQty, ':subtractingQty' => $subtractedQty));

                                    $updateItemsAfterSubtraction = $db - > prepare("UPDATE Items SET QTY = QTY + :subtractedQTY where id= :iID  ");

                                    $update_subproducts - > execute(array(':iID' => $itemId, ':subtractedQTY' => $subtractedQty));


                                }

                                if ($updateInvoice AND $insertNewItems AND $updateInvoiceAddedItems AND $updateInvoiceSubtractedItems) {
                                    echo ' <script> alert("success") </script>';
                                    exit;

                                } else {
                                    echo ' <script> alert("Error") </script>';
                                }
                            } catch (PDOException $e) {
                                echo 'Connection failed: '.$e - > getMessage();
                            }
                        }
                    }