$host = 'localhost';
$db = 'forum';
$user = 'root';
$pass = '';
$charset = 'utf8';

$dsn = "mysql:host = $host; dbname = $db; charset=$charset";
$opt = [
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
PDO::ATTR_EMULATE_PREPARES =>false,
];
$pdo = new PDO($dsn, $user, $pass, $opt);
$stmt = $pdo->query('SELECT * FROM catalogs;');
while ($row = $stmt->fetch()){
echo $row['name'] . "n";
}