$query = $db->query("SELECT * FROM ogrkulup WHERE CONCAT(ADI,' ',SOYADI,' ',GELIL) = '{$key}'")->fetchAll();
foreach($query as $key => $value) {
?><div class="alert alert-success" role="alert"><strong><i class="fas fa-check"></i> Bilgi Bulundu !</strong> </div>
<center><strong style="color:red">Detaylar</strong></center>
<br>
<center><strong>ADI : <?php echo $value["ADI"]; ?></strong>
<br>
<strong>SOYADI : <?php echo $value["SOYADI"]; ?></strong>
<br></center>
<?php
} böylemi hocam
dostum sorguyu fetchAll olarak değiştir
foreach($query as $key => $value) {
// döngüye girilecek kısım
// $query değil $value["ad soyad vs"];
}