Untitled

<html>
<head>
    <title>My first PHP website</title>
</head>
<body>
<h2>Registration Page</h2>
<a href="index.php">Click here to go back</a><br/><br/>
<form action="register.php" method="post">
    Enter Username: <input type="text" name="username" required="required"/> <br/>
    Enter Password: <input type="password" name="password" required="required" /> <br/>
    <input type="submit" value="Register"/>
</form>
</body>
</html>

<?php
if($_SERVER["REQUEST_METHOD"] == "POST"){
    $username = mysqli_real_escape_string($_POST['username']);
    $password = mysqli_real_escape_string($_POST['password']);
    $bool = true;
    $dbConnection = mysqli_connect("localhost", "root","") or die(mysqli_error()); //Connect to server
    mysqli_select_db($dbConnection, "first_db") or die("Cannot connect to database"); //Connect to database
    $query = mysqli_query($dbConnection, "Select COUNT(*) count from users WHERE username = '$username'");
    $result = mysqli_fetch_array($query);
    if(!empty($result['count'])) {
        $bool = false; // sets bool to false
        Print '<script>alert("Username has been taken!");</script>'; //Prompts the user
        Print '<script>window.location.assign("register.php");</script>'; //Redirects to register.php
    }
    if($bool) // checks if bool is true
    {
        mysqli_query($dbConnection, "INSERT INTO users (username, password) VALUES ('$username','$password')"); //Inserts the value to table users
        Print '<script>alert("Successfully Registered!");</script>'; //Prompts the user
        Print '<script>window.location.assign("register.php");</script>'; //Redirects to register.php
    }
}
?>