如何仅在付款和传递会话后将时间戳添加到数据库

I am configuring a page that adds a timestamp to a database after payment. This code should prevent clever clients from extending their subscription. It also needs to pass the Client_id to Paypal and back

In the header I have defined the start and expiry times and these are passed as sessions

session_start();
   global $wpdb;

$client_id=$_SESSION['client_id'];
$time=date("Y-m-d");
$_SESSION[expire];
$_SESSION[start];

if ($time > $_SESSION[expire])
{ echo 'Your susbcription is out of date.';
}
else {

    $timestamp = date('Y-m-d');
if(!empty($client_id)){
    $wpdb->update( 'database_field', array ('subscription'=>  $timestamp), array('id' => $client_id));
    }
    }

If you are using paypal as a payment gateway to collect amount, then i suggest to use IPN.

Instant Payment Notification (IPN) is a message service that notifies you of events related to PayPal transactions.

IPN will call only once when your customer try to do payment and he/she get success or failure.

Based on IPN data you can check that payment is successfull or not.

Please refer to this for further details

https://developer.paypal.com/docs/classic/ipn/integration-guide/IPNIntro/# https://developer.paypal.com/docs/classic/ipn/ht_ipn/#do-it

Thanks for answer. Will see if that works for me