在上一页链接和新页面之间连接产品ID

I'm almost there, but the id in this page listing product inventory:

<?php
while($productData = mysqli_fetch_array($p_query, MYSQL_ASSOC)){
echo '<a href="../product.php?id="'.$productData["id"].'">'.$productData["product_name"].'</a><br           />';
};
?>

won't connect with the product.php page code for some reason where I want to list details from the database of one product:

$id=$_GET['id'];

include_once("php_includes/db_conx.php");

$p_sql = "SELECT * FROM products where id = '$id'";
$p_query = mysqli_query($db_conx, $p_sql);

$prodData = mysqli_fetch_array($p_query, MYSQL_ASSOC);

In the address bar it is showing as 'root/product.php?id=' with no product id number.