class db {
    private $host;
    private $db_name;
    private $db_user;
    private $db_password;

    public function connect() {
        $db_name = $this->db_name;
        $db_user = $this->db_user;
        $db_pass = $this->db_password;
        $db_host = $this->host;

        $db_name = 'database name';
        $db_user = 'username';
        $db_pass = 'password';
        $db_host = 'localhost:3306';

        try {
            $connect = new PDO('mysql:dbname=$db_name;host=$db_host;', $db_user, $db_pass);
            $connect->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            echo "Connection Successfull";
        } catch(PDOException $e) {
            echo "Connection Failed : " . $e->getMessage();
        }
    }
}

$users      = new users();
    $connection = new db();
    $connect    = $connection->connect();
    $sql = $connect->prepare("SELECT * FROM users");
    $sql->execute();
    while($data = $sql->fetch(PDO::FETCH_ASSOC)) {
        echo $data['name'];
    }