title: php session always created on refresh
body: <p>I am new to PHP so have a very basic question
  I creating a page I am creating a page initially with user id and password, once user id and password are entered and submit is clicked, AJAX is called to validate that against database.
  once validation done I want to refresh the page which show more option to user
  I was thinking to use session
  but every time I refresh the page a new session is created
  I put this at the top of the page as a test and always when F5 is press I see "new session" on top of the page</p>
  
  <pre><code>&lt;?php
  if (!isset($_SESSION)){
      session_start();
      echo("new session");
  }
  else
  {
      echo("old session");
  }
  ?&gt;
  </code></pre>