Untitled

<?php
if(isset($_SESSION['id'])) {
    header("Location: user.php");
}
if(isset($_POST['register'])) {
    $db = mysqli_connect("localhost", "nunomarquina", "Amaral47",
"proyecto_ets2mp");

    $username = strip_tags($_POST['username']);
    $password = strip_tags($_POST['password']);
    $password_confirm = strip_tags($_POST['password_confirm']);
    $mail = strip_tags($_POST['email']);

    $username = stripslashes($username);
    $password = stripslashes($password);
    $password_confirm = stripslashes($password_confirm);
    $mail = stripslashes($mail);

    $username = mysqli_real_escape_string($db, $username);
    $password = mysqli_real_escape_string($db, $password);
    $password_confirm = mysqli_real_escape_string($db, $password_confirm);
    $mail = mysqli_real_escape_string($db, $mail);

    $password = md5($password);
    $password_confirm = md5($password_confirm);

    $sql_store = "INSERT INTO users (username, password, email) VALUES ('$username', '$password', '$mail')";
    $sql_fetch_username = "SELECT username FROM users WHERE username = '$username'";
    $sql_fetch_mail = "SELECT email FROM users WHERE email = '$mail'";

    $query_username = mysqli_query($db, $sql_fetch_username);
    $query_mail = mysqli_query($db, $sql_fetch_mail);

    }
?>

<!doctype html>
<html>
    <head>
        <link rel="stylesheet" href="assets/css/main.css"/>
        <title>Register form</title>
    </head>
    <body>
        <div id="login">
            <h1>Register</h1>
            <form action="register.php" method="post" enctype="multipart/form-data">
                <input placeholder="Username" name="username" type="text">
                <input placeholder="Password" name="password" type="password">
                <input placeholder="Confirm Password" name="password_confirm" type="password">
                <input placeholder="E-Mail Adress" name="email" type="text">
                <input name="register" type="submit" value="Register">
            </form>
            <h2>Tienes una cuenta?</h2>
            <h2><a href="login.php">Inicia Sesion</a></h2>
        </div>
    </body>
</html>