<?php
session_start();
$username = $_POST['username'];
$password = $_POST['password'];


$pdo = new PDO('mysql:host=localhost;dbname=web', 'webstuff', 'Schei// auf Pa$$w0rter!');
$statement = $pdo->prepare('SELECT id, name, authentication_algorithm, authentication_string FROM users WHERE name = :username;');
$result = $statement->execute(array('username' => $username));
if ($result) {
  //existing user name
  print_r($statement->fetch());
} else {
  //wrong user name
}
?>