register user php

<div class="col-md-6">
                                                <div class="form-floating mb-3 mb-md-0">
                                                        Username
                                                        <label for="email"></label>
                                                        <input type="text" name="username" id="email" class="form-control" placeholder="[email protected]">
                                                </div>
                                                </br>
                                                <div class="form-floating mb-3 mb-md-0">
                                                        Password
                                                        <label for="password"></label>
                                                        <input type="password" name="password" id="password" class="form-control" placeholder="password">
                                                </div>
                                                </br>
                                                <button type="submit" name="register" class="btn btn-info">Register</button>
                                        </form>
                                    </div>
                                    <div class="text-center py-3">
                                    <div class=""><a href="login.php">Have an account? Go to login</a></div>

<?php
include "mysql_mysqli.inc.php";

session_start();

//membuatkoneksi
$hostname_conn  = "localhost";
$database_conn  = "db_komkordik";
$username_conn  = "root";
$password_conn  = "";
$conn = mysql_connect($hostname_conn,$username_conn,$password_conn) 
        or trigger_error(mysql_error(),E_USER_ERROR);



?> 

//daftar
if(isset($_POST['register'])){
 

    $username = $_POST['email'];
    $password = $_POST['password'];

    $epassword = password_hash($password, PASSWORD_DEFAULT);

    //insert into database
    $insert = mysqli_query($conn,"INSERT INTO kom_user (email,password) VALUES ('$email','$epassword')");

    if($insert){
        //jika berhasil
        header('location:index.php');
    } else {
        //jika gagal
        echo '
        <script>
            alert("register gagal");
            window.location.href="register.php";
        </script>
        ';
    }
}