invisio v2.0

<?php
    session_start();
    include('../../../config/main_function.php');
    $secure = "cAh3DrJACzw4RbU";
    $connection = connectDB($secure);

$date_now = date('Y-m-d');

if ($connection) {

$coupon_code = mysqli_real_escape_string($connection, $_POST['coupon_code']);

$sql = "SELECT * FROM tbl_discount_coupon WHERE coupon_code = '$coupon_code' ";
        $res = mysqli_query($connection, $sql);
        $num_coupon = mysqli_num_rows($res);
        $row = mysqli_fetch_assoc($res);

$payment_id  =  mysqli_real_escape_string($connection, $_POST['payment_id']);
        if ($num_coupon > 0) {

if ($date_now > $row['expire_date']) {
                $arr['result'] = 'expire_date';
            } else {
                $sql_update = "UPDATE tbl_member_payment SET coupon_id = '{$row['coupon_id']}' WHERE payment_id  = '$payment_id'";
                $res_update = mysqli_query($connection, $sql_update)  or die($connection->error);

if ($res_update) {
                    $arr['result'] = 1;
                } else {
                    $arr['result'] = 0;
                }
            }
        } else {
            $arr['result'] = 'no_coupon';
        }
    } else {
        $arr['result'] = 9;
    }

mysqli_close($connection);
    echo json_encode($arr);
    ?>