PHP - PDO - Filtreleme ve Array listeleme

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

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

<form action="sec.php" method="post">
<select name="kategoriler[]" multiple>
<option value="1">Araba</option>
<option value="2">TV</option>
<option value="3">Bilgisayar</option>
</select>
<input type="submit">
</form>

sec.php
$kategoriler = $_POST['kategoriler'];
$alanlar= str_repeat('?, ', count($kategoriler) - 1) . '?';
$query = $db->prepare("SELECT * FROM urunler WHERE c_id IN ($alanlar)");
$query->execute($kategoriler);
$query = $query->fetchAll(PDO::FETCH_OBJ);
print_r($query);

    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();
    }

$checklist = $_POST['aramasec'];
foreach($checklist as $list) {
$alt_kategoriler[] = $list['id'];
}
if(is_array($alt_kategoriler) && count($alt_kategoriler) >= '1'){
$alt_kategoriler = implode(',', $alt_kategoriler);
$depourunlersor=$db->prepare("SELECT * FROM depourunler WHERE alt_kategori IN($alt_kategoriler 9)");
$depourunlersor->execute();
}