Adding Page Counter to Each Classified Ad - php

Question

I am trying to add a page counter to each classified Ad just like to one on ebay for example. There is a page counter that increases whenever a user clicks on an item.
Here is why I have a problem:
itemlist.php
$query="SELECT post_id, title FROM md_post WHERE category='cars' ORDER BY timeStamp desc";
$result= mysql_query($query) or die (mysql_error());
while($row = mysql_fetch_array($result)){
echo "<a href='itemdescription.php?id=".$row['post_id']."'>". $row['title']."</a>";
so When I click on an item title with id of 3, i would be direction to the itemdescription.php?id=3
My problem is when I add a page counter to itemdescription.php, I get a counter that increments even when I click on different items.
the counter will be 1 for itemdescription.php?id=3
and 2 for itemdescription.php?id=4
I want each ad to have a stand-alone page counter
UPDATE:
Sorry I did not include the code for itemdescription.php page since there is no much in it. Here it is:
<div id="content">
<?php
$query="SELECT name, email, category, region, city, title, price, description FROM md_post WHERE category='cars' AND post_id='$_GET[id]'";
$result= mysql_query($query) or die (mysql_error());
$row = mysql_fetch_array($result);
echo $row['category'] . " in ". $row['city'];
echo $row['title']. " - price is -". $row['price']."$"." ". "<br /><br />";
echo "description"."<br /><br />";
echo $row['description'];
echo $row['name'] . " - ". $row['email']. " region:". $row['region'] . "<br /><br />";
This page is only displaying the ad. e.g. displaying info like price, title, city ...etc
I want to include a stand-alone page counter at the bottom of this page, but when I tried, the counter was not unique for a specific item/ad. It was shared by all items/ads

Answer 1

$_SERVER['REQUEST_URI']
gives you the URL with parameters. you need to update your counter unique to that, not without parameters. if you share more of your codes, we can help you with integration.

Answer 2

I solved it. Thanks for your help anyway. This code below will create a text file that checks the id of the url and counts hits based on the unique ad id. This will prevent mixing counting ads or posts.
<p> this ad has this number of visits </p>
<?php
//--------------------Page counter-------------------------
$stored = "counters/".$_GET['id'].".txt";
function displayHitThingy($stored) {
$fp = #fopen($stored,"r");
$stuff = #fgets($fp,9999);
#fclose($fp);
$fp = fopen($stored,"w");
$stuff += 1;
print "$stuff";
fputs($fp, $stuff);
fclose($fp);
}
displayHitThingy($stored);
//________________________________________________________________________
?>