Hi, sir Update query is not working

if ($invoice_no != null) {
                // echo "This is last invoice number" . $invoice_no;
                for ($i = 0; $i < count($ar_price); $i++) {
                    $rem_qty = $ar_tqty[$i] - $ar_qty[$i];
                    if ($rem_qty < 0) {
                        echo "Product Out Of Stock!";
                    } else {
                        $modelpro = new productModel();

                        $db      = \Config\Database::connect();
                        $builder = $db->table('product');
                        //Update Product stock
                        $updateQuantity = [
                            'Quantity' => $rem_qty,
                        ];
                        // if ($modelpro->update($updateQuantity)->where('productName', $ar_pro_name[$i])) {
                        //     echo "updated";
                        // } else {
                        //     echo "update query error";
                        // }
                        $builder->where('productName', $ar_pro_name[$i]);
                        $builder->update($updateQuantity);
                    }
                }
            }

@sandeep1992,

We need a little more information. What version of CI are you using? What error messages are you seeing?

if ($invoice_no != null) {
                // echo "This is last invoice number" . $invoice_no;
                for ($i = 0; $i < count($ar_price); $i++) {
                    $rem_qty = $ar_tqty[$i] - $ar_qty[$i];
                    if ($rem_qty < 0) {
                        echo "Product Out Of Stock!";
                    } else {
                        $modelpro = new productModel();


                        $modelpro
                            ->where('productName', $ar_pro_name[$i])
                            ->set(['Quantity' => $rem_qty])
                            ->update();
                    }

                    $modelInvo = new invoiceDetailModel();
                    $saveInvoiceDetail = [
                        'invoice_no'   => $invoice_no,
                        'product_name' => $ar_pro_name[$i],
                        'price'        => $ar_price[$i],
                        'qty'          => $ar_qty[$i],
                    ];

                    $modelInvo->save($saveInvoiceDetail);
                }
            }

by the code and approach - this seems to be done in a controller - just a guess

maybe your `$invoice_id` is 0
maybe your `$invoice_id` is ""

last option is most likely as that's how empty input values are posted - as empty strings, but never NULLs
Maybe for your build php function empty() could do a magic?