title: How to make CodeIgniter accept "query string" URLs?
body: <p>According to CI's docs, CodeIgniter uses a <strong>segment-based approach</strong>, for example:</p>
  
  <pre><code>example.com/my/group
  </code></pre>
  
  <p>If I want to find a specific group (id=5), I can visit </p>
  
  <pre><code>example.com/my/group/5
  </code></pre>
  
  <p>And in the controller, define</p>
  
  <pre><code>function group($id='') {
      ...
      }
  </code></pre>
  
  <p>Now I want to use the traditional approach, which CI calls "query string" URL. Example:</p>
  
  <pre><code>example.com/my/group?id=5
  </code></pre>
  
  <p>If I go to this URL directly, I get a <strong>404 page not found</strong>. So how can I enable this?</p>