grouping by class in groups

Run out of ideas... I need to group all entries form database. There are fields ID, NAME, CLASS, CREATED. Output would look like this:

<h2>3. Class</h2>
<div class="cont">
 3rd class entries..
</div>

<h2>8. Class</h2>
<div class="cont">
 8th class entries..
</div>

... and more

So if there are entries with class 3, they all go in their own <div> with their own heading - <h3>. The s开发者_运维百科ame thing with 8, 9,10, 545,5357 etc. Numbers within <h3>...</h3> are taken form the table, so they do not come from a counter like $i++.

How to achieve that? I hope you got my idea.

Something like this will do the trick...

<?php      

  $rs = mysql_query('select id, name, class, created from mytable order by class ASC');
  while( $row = mysql_fetch_assoc($rs)) {
     $is_new_class = ( !isset($last_class_num) || ($row['class'] != $last_class_num) );
     if( $is_new_class && isset($last_class_num) ) {
       echo "</div>";
     }
     if( $is_new_class ) {
       echo "<h2>{$row['class']}. Class</h2>";
       echo "<div class=\"cont\">";
     }
     echo "NAME: {$row['name']}, <br/>";
     echo "CREATED: {$row['created']}";
     $last_class_num = $row['class'];
  }
  if( isset($last_class_num) {
    echo "</div>";
  }

[edit: I originally misunderstood the example given by the OP, so I've updated the answer to fix that. Also, fixed some type-os in my original example. And cleaned up syntax to make it more readable. (sorry if there was any confusion)]