title: php mysql where IN clause
body: <p>I have a simple query:</p>
  
  <pre><code>$user_id = $_SESSION['user_id'];
  
  SELECT *  FROM pages WHERE user_id IN($user_id);
  </code></pre>
  
  <p>field user_id in pages tables has the following format 1,3,5,...
  it contains multiple user_id</p>
  
  <p>What I need is to select all rows based on logged in user_id. 
  The above attempt does not works, it only picks up the first number.</p>