index.php

<html>
	<head>
        <title>Login</title>
    </head>
	<link rel="stylesheet" href="asset/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
	<!--asset js-->
	<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
	<script src="asset/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
    <body>
        <div class="container">
            <div class="row">
                <div class="col-sm-9 col-md-7 mx-auto">
                <!--gunakan card di bootstrap-->
                    <h3 class="text-center"> Form Login </h3><hr>
                    <div class="card my-5">
                        <div class="card-body">
                            <form action="" method="POST">
                                <label>Username :</label>
                                <input type="text" name="username" class="form-control" placeholder="Masukkan Username" required>
                                <label>Password :</label>
                                <input type="password" name="password" class="form-control" placeholder="Masukkan Password" required>
                                <br>
                                <input type="submit" name="login" value="Login" class="button">
                            </form>
                            <!---koneksi php-->
							<?php
								include 'config.php';
								$user = mysqli_real_escape_string($db, @$_POST['username']);
								$pass = mysqli_real_escape_string($db, @$_POST['password']);
								$kirim = @$_POST['login'];
								//check jika user klik login
								if (ISSET($kirim)) {
									echo "Tertekan";
									$query = mysqli_query($db,"Select * from login where Username = '$user' and Password = SHA1('$pass')") or die(mysqli_error($db));
									$cek   =mysqli_num_rows($query);
									echo $cek;
									//jika use ada
									if ($cek >0) {
										echo "<script>
										window.alert('Login telah berhasil');
										window.location.href='menu.php';
										</script>";
									} else {
										echo "<script>
                                        window.alert('Maaf, Login gagal');
                                        window.location.href='index.php';
										</script>";
									}
								}
							?>
                        </div>
					</div>
				</div>
			</div>
		</div>
	</body>
</html>