How to change a variable in a URL?

[BaseballGraphs]

I am trying to allow users to toggle between various metrics that I am covering and having that information update on the page.

The way that my data is interpreted on my page is by using variable in the URL. The standard structure is: /frontend.php?p=502&s=56&y=2010

Where p = player id
s = statistic id
and y = year

I am trying to implement a drop down selection list on the page where users can change the statistic.

Here is my code. Any help would be very appreciated!

<form action="/frontend.php?p=<?= $player_id; ?>&" method="get" >
<select id="stat" name="s" style="width: 215px">
<option>-- Statistic --</option>
<?php foreach( getStatistics() as $id => $name ){ ?>
  <option value="<?= $id; ?>"><?= $name; ?></option>
<?php } ?>
</select>
<input type="submit" value="Graph" style="height: 25px; width: 200px">
</form>
 

When this form is submitted I only get http://tyrone.pae.me/frontend.php?s=4 this URL to show. I need to be able to maintain the 'p' value and the 'y' value but alter the 's' value.

[dlite922]

create hidden input fields and put in the values you want to preserve.

 
<input type="hidden" name="p" value="<?php echo $_GET['p'];?>" 
 
 

Same for Y and S.

If there's a hidden field for S, then an actual select field for S, then the value from the S field will be counted because it comes later and gets overwritten.

Dan