<?php
    $host = "localhost";
    $user = "root";
    $pass = "root";
    $name = "test";
    $link = mysqli_connect($host, $user, $pass, $name);

    session_start();

  if (!empty($_GET)) {
    $surname = $_GET['surname'];
        $name = $_GET['name'];
        $query = "INSERT INTO users (surname,name) VALUES ('$surname','$name')";
        mysqli_query($link, $query) or die(mysqli_error($link));
        $_SESSION['flash'] = 'форма успешно сохранена';
    header('Location: index.php');
  };
    if(isset($_SESSION['flash'])){
        echo $_SESSION['flash'];
        unset($_SESSION['flash']);
    };

?>
<form method="GET">
    <input name="surname" placeholder="Фамилия"></br>
    <input name="name" placeholder="Имя"></br>
    <input type="submit">
</form>