title: Pass query string variable to WordPress page template
body: <p>I have a fully-functional WordPress site with a URL structure like this:</p>
  
  <pre><code>http://example.com/friendlyurl/
  </code></pre>
  
  <p>But I would like to be able to pass an ID number like this (or whatever URL structure would work):</p>
  
  <pre><code>http://example.com/friendlyurl/?id=123
  </code></pre>
  
  <p>I have a custom page template that will handle everything from there, I just need a simple way to get the number to the page template. I.e.:</p>
  
  <pre><code>$id=trim($_GET["id"]);
  </code></pre>
  
  <p>I am not a WordPress whiz, just looking for a simple solution here to solve a problem. Would appreciate any advice or direction.</p>
  
  <p>Thank you!</p>