View difference between Paste ID: BgNFuZrA and qmNDd02j

 <?php
 
 session_start();
 
 $pdo = new PDO("mysql:host=localhost;dbname=database", 'username', 'password');
 
 if(isset($_POST['formreg'])) {
 	$username = $_POST['user_input'];
 	$password = $_POST['pass_input'];
 
 	$query = $pdo->prepare("INSERT INTO users (user,pass) VALUES (:user_token,:pass_token)");
 	$values = array(
 		"user_token" => $username,
 		"pass_token" => sha1($password)
 	);
 	$query->execute($values);
 }
 
 if(isset($_POST['formlog'])) {
 	$username = $_POST['user_input'];
 	$password = $_POST['pass_input'];
 
 	$query = $pdo->prepare("SELECT * FROM users WHERE user=:user_token LIMIT 1");
 	$values = array(
 		"user_token" => $username
 	);
 	$query->execute($values);
 	$row = $query->fetch(PDO::FETCH_ASSOC);
 	if($row !== false) {
 		if($row["pass"] === sha1($password)) {
 			echo "Login success.";
 			$_SESSION["username"] = $row["user"];
 		} else {
 			echo "Wrong password.";
 		}
 	} else {
 		echo "Username doesn't exist.";
 	}
 }
 
 if(isset($_POST['formlogout'])) {
 	session_destroy();
 }
 
 ?>
 
 <h1>Login</h1>
 <form action="index.php" method="post">
 username: <input type="text" name="user_input"><br>
 password: <input type="password" name="pass_input"><br>
 <input type="hidden" name="formlog" value="1">
 <input type="submit">
 </form>
 
 <?php if(isset($_SESSION['username'])): ?>
 <h1>Logout</h1>
 <form action="index.php" method="post">
 <input type="hidden" name="formlogout" value="1">
 <input type="submit">
 </form>
 <?php endif; ?>
 
 <h1>Register</h1>
 <form action="index.php" method="post">
 username: <input type="text" name="user_input"><br>
 password: <input type="password" name="pass_input"><br>
 <input type="hidden" name="formreg" value="1">
 <input type="submit">
 </form>