title: Get the value with one mysql-query
body: <p>With the following query I get the values of the different classes</p>
  
  <pre><code>$query = xtc_db_query("-- " . __LINE__ . __FILE__ . "
    SELECT value
    FROM   " . TABLE_ORDERS_TOTAL . "
    WHERE  orders_id = " . $last_order . "
    AND    class = 'ot_shipping'
  ");
  $orders_total_shipping = xtc_db_fetch_array($query);
  $query = xtc_db_query("-- " . __LINE__ . __FILE__ . "
    SELECT value
    FROM   " . TABLE_ORDERS_TOTAL . "
    WHERE  orders_id = " . $last_order . "
    AND    class='ot_tax'
  ");
  $orders_total_tax = xtc_db_fetch_array($query);
  $query = xtc_db_query("-- " . __LINE__ . __FILE__ . "
    SELECT value
    FROM   " . TABLE_ORDERS_TOTAL . "
    WHERE  orders_id = " . $last_order . "
    AND    class='ot_total'
  ");
  $orders_total = xtc_db_fetch_array($query);
  </code></pre>
  
  <p>Is it possible to get the values with one query?</p>