$STH = $DBH->query('SELECT Tid  from Playlist ');
$STH->setFetchMode(PDO::FETCH_OBJ);
$result = $STH->fetch();

while($result = mysql_fetch_array($result)) {
    $ids_array[] = $result['Tid'];
}

$stmt = $DBH->query("SELECT Tid  from Playlist");
$result = $stmt->fetchAll(PDO::FETCH_OBJ);
$ids = array_map(function($v){
    return $v->Tid;
}, $result);

print_r($ids);

$stmt = $DBH->query("SELECT Tid from Playlist");
$ids_array = $stmt->fetchAll(PDO::FETCH_COLUMN);