pardon yanlış okumuşum.
veritabanından $_GET ile veri çekilmez gözden kaçırdığınız biryer var kodun tamamını verebilirseniz daha net çözüm üretebiliriz.
tabi hocam, kodun tamamı aşağıdaki gibi.
<?php
define("DATA","data/");
session_start();
include('veritabani.php');
// Validating Session
if(strlen($_SESSION['userlogin'])==0)
{
header('location:giris-yap.php');
}
else{
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>Dashboard</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<!-- App favicon -->
<link rel="shortcut icon" href="assets/images/favicon.ico">
<!-- App css -->
<link href="assets/css/bootstrap.min.css" rel="stylesheet" type="text/css" id="bootstrap-stylesheet" />
<link href="assets/css/icons.min.css" rel="stylesheet" type="text/css" />
<link href="assets/css/app.min.css" rel="stylesheet" type="text/css" id="app-stylesheet" />
</head>
<body class="left-side-menu-dark topbar-light">
<body>
<!-- Begin page -->
<div id="wrapper">
<?php
include_once(DATA."header.php");
?>
<?php
include_once(DATA."sidebar.php");
?>
</div>
<div class="content-page">
<div class="content">
<!-- Start Content-->
<div class="container-fluid">
<!-- start page title -->
<div class="row">
<div class="col-12">
<div class="page-title-box">
<div class="page-title-right">
<ol class="breadcrumb m-0">
<li class="breadcrumb-item"><a href="javascript: void(0);">Uplon</a></li>
<li class="breadcrumb-item active">Dashboard</li>
</ol>
</div>
<h4 class="page-title">Dashboard</h4>
</div>
</div>
</div>
<!-- end page title -->
<div class="col-xl-5">
<div class="card-box">
<h4 class="header-title mb-3">Top Contracts</h4>
<div class="table-responsive">
<table class="table mb-0 table-sm mb-0">
<thead>
<tr>
<th>#</th>
<th>Ürünler</th>
<th>Mevcut Stok</th>
<th>İşlem</th>
</tr>
</thead>
<tbody>
<?php
$envlistesi = $vtbaglanti->prepare("SELECT * FROM stok HAVING mevcutadet < 10 ORDER BY mevcutadet ASC");
$envlistesi->execute();
while ($cek = $envlistesi->fetch(PDO::FETCH_OBJ)) {?>
<tr>
<th scope="row"><?=$cek->id?></th>
<td><?=$cek->urunler?></td>
<td><?php
$mevcutadet = isset($_GET['mevcutadet']) ? $_GET['mevcutadet'] : '';
if (empty($mevcutadet) || $mevcutadet == 0) {
echo "Stok Yok!";
} else {
echo "$mevcutadet Adet";
}
?></td>
<td><a href="envanterduzenle.php?id=<?=$cek->id?>"><button type="button" class="btn btn-info btn-xs" ><i class="fas fa-pencil-alt"></i> Stok Düzenle</button></a></td>
</tr>
<?php } ?>
</tbody>
</table>
</div>
</div>
</div><!-- end col-->
</div>
<!-- end row -->
</div> <!-- end container-fluid -->
</div> <!-- end content -->
<!-- Footer Start -->
<!-- end Footer -->
</div>
<!-- ============================================================== -->
<!-- End Page content -->
<!-- ============================================================== -->
</div>
<!-- END wrapper -->
<!-- Right bar overlay-->
<div class="rightbar-overlay"></div>
<!-- Vendor js -->
<script src="assets/js/vendor.min.js"></script>
<!--Morris Chart-->
<script src="assets/libs/morris-js/morris.min.js"></script>
<script src="assets/libs/raphael/raphael.min.js"></script>
<!-- Dashboard init js-->
<script src="assets/js/pages/dashboard.init.js"></script>
<!-- App js -->
<script src="assets/js/app.min.js"></script>
</body>
</html>
<?php } ?>