title: Grab row(s) with highest value in specific colum
body: <p>I've got a simple table that is storing unique IDs tied to a download. What I'm trying to do is generate a CSV of the most recent IDs created. Each time keys are generated (anywhere from 1 to 100 keys at a time), a UNIX timestamp is stored with those keys.</p>
  
  <p>I have the CSV file generating just fine, but I can't get the MAX function to work properly. My report generator is below:</p>
  
  <pre><code>// output headers so that the file is downloaded rather than displayed
  header('Content-Type: text/csv; charset=utf-8');
  header('Content-Disposition: attachment; filename=codes.csv');
  
  // create a file pointer connected to the output stream
  $output = fopen('php://output', 'w');
  
  // output the column headings
  fputcsv($output, array('Unique Codes'));
  
  // fetch the data
  /** database username and pass removed **/
  $rows = mysql_query('SELECT uniqueid FROM downloadkeys');
  
  // loop over the rows, outputting them
  while ($row = mysql_fetch_assoc($rows)) fputcsv($output, $row);
  </code></pre>