if (isset($_POST['aramayap'])) {
$checklist = $_POST['aramasec'];
foreach($checklist as $list) {
    $alt_kategoriler = $list.',';
    $depourunlersor=$db->prepare("SELECT * FROM depourunler WHERE alt_kategori IN($alt_kategoriler 9)");
    $depourunlersor->execute();
}
    }else{
        $depourunlersor=$db->prepare("SELECT * FROM depourunler");
        $depourunlersor->execute();
    }