ExpressionEngine Alternating Rows Table

<?php $oddOrEven = "odd"; ?>
{exp:channel:entries channel="office-vacancies" dynamic="no" category="{segment_3_category_id}"}            
<tr class="<?php echo($oddOrEven); ?>">
  <td>{title}</td>
  <td>{office-floor}</td>
  <td>{office-sqft}</td>
  <td>{office-rent}</td>
  <td>{office-type}</td>
  <td style="text-align: center">{if "{office-floorplan}" != ""}<a href="{office-floorplan}" target="_blank"><img src="/img/pdf.gif" /></a>{/if}</td>
</tr>
 
{if no_results}
<tr class="odd">
  <td>None</td>
  <td></td>
  <td></td>
  <td></td>
  <td></td>
  <td></td>
</tr>
{/if}
 
<?php
if ($oddOrEven == "odd") {
  $oddOrEven = "even";
} else {
  $oddOrEven = "odd";
}
?>
{/exp:channel:entries}