Untitled

<!DOCTYPE html>
<html lang="en-US">
    <head>
        <meta charset="UTF-8">
        <title>create.html</title>
        <script src="script.js"></script>
        <link rel="stylesheet" type="text/css" href="style.css">
    </head>
    <body bgcolor="pink">
        <center>
            <form action="create.php" method="post">
                <label>Username</label>
                <input type="text" name="username"><br>
                <label>Password</label>
                <input type="password" name="password"><br>
                <label>Re-enter Password</label>
                <input type="password" name="confirm_password"><br>
                <button type="submit">Create Account</button>
            </form>
        </center>
    </body>
</html>

<!DOCTYPE html>
<html lang="en-US">
    <head>
        <meta charset="UTF-8">
        <title>create.php</title>
    </head>
    <body bgcolor="pink">
        <?php

            $servername = "localhost";
            $username = "XXXXXXXXXX"; // Not shown
            $password = "XXXXXXXXXX"; // Not shown
            $dbname = "Database";

            //Create connection
            $mysqli = new mysqli($servername, $username, $password, $dbname);

            //Test connection
            if ($mysqli->connect_error) {
                die("Connection failed: " . $mysqli->connect_error);
            }

            $new_user_usr = filter_input(INPUT_POST, 'username');
            $new_user_pwd = filter_input(INPUT_POST, 'password');
            $new_user_pwd_conf = filter_input(INPUT_POST, 'confirm_password');

            $sql = "SELECT usr, pwd FROM Users";
            $result = $mysqli->query($sql);

            if($result->num_rows > 0) {

                /* If passwords don't match */
                if($new_user_pwd !== $new_user_pwd_conf) {
                    die("Passwords don't match");
                }

                /* If password isn't between bounds */
                if(strlen($new_user_pwd) <= 7 || strlen($new_user_pwd) >= 13) {
                    die("Password not long enough! Must be at least 8 characters long, but not greater than 12 characters");
                }

                /* If username is the same as password*/
                if($new_user_usr === $new_user_pwd) {
                    die("Username cannot equal password!");
                }

                while($row = $result->fetch_assoc()) {
                    if($row['usr'] === $new_user_usr) {
                        die("Username already taken");
                    }
                }

                $add = "INSERT INTO Users (usr, pwd) VALUES ('$new_user_usr', '$new_user_pwd')";

                echo $mysqli->query($add) ? "user created successfully" : "Error: " . $add . "<br>" . $mysqli->error;

            }

        ?>
    </body>
</html>