title: Add (sum) variable to existing value in database
body: <p>I have database with column <code>"kredit"</code>. I want to add <code>$dobitak</code> to <code>kredit</code>.</p>
  
  <p>So if is in database <code>kredit=10</code>, and <code>$dobitak=15 kredit+dobitak=25</code> but my code return me <code>kredit=15</code> in database.</p>
  
  <pre><code>$sql = "UPDATE user
      SET  kredit='kredit' + '".$dobitak."'
      WHERE id='" . $info['user_id'] . "'";
  </code></pre>
  
  <p>What I need to change to get correct result in database?</p>