title: Codeigniter batch update raises error about index
body: <p>The following code in codigniter gives me an error to update array:</p>
  
  <pre><code>$query="UPDATE sell_rate SET price='$price' WHERE code='$code'";
                  $this-&gt;db-&gt;query($query);
  </code></pre>
  
  <p>The error is: </p>
  
  <blockquote>
    <p>You must specify an index to match on for batch updates</p>
  </blockquote>
  
  <p>Please help me fixing this.</p>