How to insert multiple form fields data with single invoice no in php mysql

Question

i'm working in a project invoice system based on PHP/Mysqli with Jquery ajax. Invoice table structure is: table_invoice -> fields are (id, invoice_no, product, rate, qty). Add invoice form looks like:

<form action="" method="post" id="addForm">
    <input type="text" name="productName[]" placeholder="" class="form-control proList" autocomplete="off" />
    <input type="text" name="productRate[]" placeholder="" class="form-control" autocomplete="off" />
    <input type="text" name="productQuantity[]" placeholder="" class="form-control" autocomplete="off" />
    <input type="hidden" name="invoiceNo" value="19299092" />
    <input type="hidden" name="action" id="action" value="insert" />
    <button type="submit" name="submit" id="submit" class="btn btn-success"><i class="fa fa-plus"></i> Save</button>
</form>

in php file

<?php
include("connection.php");
if($_POST["action"] == 'insert'){
    $invoice = $_POST["invoiceNo"];
    $productName = $_POST["productName"];
    $productRate = $_POST["productRate"];
    $productQuantity = $_POST["productQuantity"];
    for($i=0;$i < count($productName);$i++){
         $query = mysqli_query($conn,"INSERT INTO tbl_invoice(invoice_no,product,rate,qty) VALUES('".$invoice[$i]."','".$productName[$i]."','".$productRate[$i]."','".productQuantity[$i]."')");
    }
}

MYSQL TABLE:

19299092, Product 1, 100, 10
0,        Product 2, 150, 20
0,        Product 3, 200, 20

where's the problem in query or form?

Answer 1

sorry for not having enough reputation to comment

same invoice number so you don't have to use index (say field: id is auto increment)

you may use the following query statement:

"INSERT INTO 
tbl_invoice 
SET invoice_no = '" . $invoice . "', 
    product = '" . $productName[$i] . "', 
    rate = '" . $productRate[$i] . "', 
    qty = '" . $productQuantity[$i] . "'"

Answer 2

Change query like. You don't need to pass index with $i in invoice no because invoice no is not in an array.

 $query = mysqli_query($conn,"INSERT INTO tbl_invoice(invoice_no,product,rate,qty) VALUES('".$invoice."','".$productName[$i]."','".$productRate[$i]."','".productQuantity[$i]."')");

Answer 3

<input type="hidden" name="invoiceNo" value="19299092" />

Your invoice no is a value you can insert without an array

for($i=0;$i < count($productName);$i++){
         $query = mysqli_query($conn,"INSERT INTO tbl_invoice(invoice_no,product,rate,qty) VALUES('".$invoice."','".$productName[$i]."','".$productRate[$i]."','".productQuantity[$i]."')");
    }

Try this. Hope It will helps.