<?php
$error='';
 $login=$_POST['login'];
 $haslo=$_POST['haslo1'];
 $email=$_POST['email'];
 $data=$_POST['data'];
 $plec=$_POST['plec'];

$conn = mysqli_connect('localhost','root','','forum');
     $sql="INSERT INTO `uzytkownicy`(login, haslo, email ,data , plec) VALUES ('$login','$haslo','$email','$data' , '$plec')";
echo $login;

if ($conn->query($sql) === TRUE) {
    echo "New record created successfully";
    header("Location: index.html");
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

     $conn->close();

?>