can you fix my problem about php and mysql?

mysql and my php can’t connect can you fix my problem please i need for test
this is database
this is code php
this is result after run that code (fatal eror)

<?php
require_once "../function.php";
session_start();

$host = "localhost";
$username = "root";
$password = "";
$database = "dbpariwisata"; 

// Koneksi ke database
$koneksi = mysqli_connect($host, $username, $password, $database);
 
// Cek apakah form telah disubmit
if($_SERVER["REQUEST_METHOD"] == "POST") {
    // Mengambil data yang diinputkan pada form login
    $username = $_POST['username'];
    $password = $_POST['password'];
    
    // Query untuk mencari user dengan username dan password yang sesuai
    $query = "SELECT * FROM users WHERE username='$username' AND password='$password'";
    $result = mysqli_query($koneksi, $query);
 
    // Jika data user ditemukan
    if(mysqli_num_rows($result) == 1) {
        // Buat session dan redirect ke halaman home
        $_SESSION['login'] = true;
        header("location: home.php");
    } else {
        // Jika data user tidak ditemukan
        echo "<script>alert('Username atau password salah');</script>";
    }
}
?>

i hope this problem can finished