Using a for loop to insert into mysql - php

Question

So I have a form with 4 array inputs. When I hit submit it only submits the first array values. ID is the current session holder to make sure that it creates multiple rows with the same ID. I'm trying to have it loop through and insert multiple products under the same ID. Any ideas?
session_start();
$conn = new mysqli("$server", "$user_name", "$password", "$database");
$productName = $_POST['productName'];
$productPrice = $_POST['productPrice'];
$productDescription = $_POST['productDescription'];
$productImage = $_POST['productImage'];
$id = $_SESSION['id'];
$productNameCount = count($productName);
if (isset($productName) && isset($productPrice) && isset($productDescription) && isset($productImage)) {
for ($i = 0; $i < $productNameCount; $i++) {
$productNumber = $i + 1;
$sql .= "INSERT INTO Products (id, productNumber, productName, productPrice, productDescription, productImage)
VALUES ('$id', '$productNumber', '$productName[$i]', '$productPrice[$i]',
'$productDescription[$i]', '$productImage[$i]');";
}
$conn->query($sql);
}
mysqli_close($conn);

Answer 1

First you have to find a way to get whole array.
I will write a small example:
var jsonString = JSON.stringify(array_in_javascript);
This is a in javascript.
And then in PHP:
$names = json_decode(stripslashes($_POST['jsonString']));
You must find a way related to your code.
also you can benefit from prepare statement to insert multiply records.