saveInvoiceProcess.php

<?php

session_start();
include "connection.php";

if(isset($_SESSION["u"])){

    $order_id = $_POST["o"];
    $product_id = $_POST["p"];
    $email = $_POST["e"];
    $amount = $_POST["a"];
    $qty = $_POST["q"];

    $product_rs = Database::search("SELECT * FROM `product` WHERE `id` = '".$product_id."' ");
    $product_data = $product_rs->fetch_assoc();

    $current_qty = $product_data["qty"];
    $new_qty = $current_qty - $qty;

    Database::iud("UPDATE `product` SET `qty` = '".$new_qty."' WHERE `id` = '".$product_id."' ");

    $d= new DateTime();
    $tz = new DateTimeZone("Asia/Colombo");
    $d->setTimezone($tz);

    $date = $d->format("Y-m-d H:i:s");

    Database::iud("INSERT INTO `invoice` (`order_id` , `date` , `total` , `invoice_qty` , `status` , `product_id` , `users_email`)
    VALUES ('".$order_id."' , '".$date."' , '".$amount."' , '".$qty."' , '0' , '".$product_id."' , '".$email."')");

    echo("success");

}else{
    echo("Please login to your account");
}

?>