login.php

<?php
    session_start();

    include_once('config.php');

    $username = $_POST['uname'];
    $password = $_POST['pw'];

    $data = mysqli_query($conn, "SELECT * FROM kasir where username='$username' and password='$password'");

    $cek = mysqli_num_rows($data);

    if($cek>0){
        $_SESSION['uname'] = $username;
        $_SESSION['status'] = "login";
        header("location:barang.php");
    }else{
        header("location:index.php?pesan=gagal");
    }
?>