title: How to expire the activation link in PHP?
body: <p>I have a php script that sends an activation link via email to the users so they can activate their account. The link is like this: <code>mysite.com/activation.phpid?id=20</code></p>
  
  <p>How can I create the link to expire after 24 hours?</p>
  
  <p>I haven't tried anything as I couldn't find anything to teach me how to do it. all I know is that I might be able to do this by storing something in mysql but how?</p>
  
  <p>it will be great if someone could tell me the step by step instruction please.</p>
  
  <p>Thanks</p>