index.php

<?php

    //memulai session
    session_start();

    //jika ada session, maka akan diarahkan ke halaman dashboard admin
   if(isset($_SESSION['id_user'])){

        //mengarahkan ke halaman dashboard admin
     header("Location: ./admin.php");
   die();
    }

    //mengincludekan koneksi database
    include "koneksi.php";

?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <meta name="description" content="">
    <meta name="author" content="">

    <title>Aplikasi Jasa Cuci</title>

    <!-- Bootstrap core CSS -->
    <link href="css/bootstrap.css" rel="stylesheet">
	<style type="text/css">
	body {
	  padding-top: 40px;
	  padding-bottom: 40px;
	  background-color: #eee;
	}

	.form-signin {
	  max-width: 330px;
	  padding: 15px;
	  margin: 0 auto;
	}
	.form-signin .form-signin-heading,
	.form-signin .checkbox {
	  margin-bottom: 10px;
	}
	.form-signin .checkbox {
	  font-weight: normal;
	}
	.form-signin .form-control {
	  position: relative;
	  height: auto;
	  -webkit-box-sizing: border-box;
		 -moz-box-sizing: border-box;
			  box-sizing: border-box;
	  padding: 10px;
	  font-size: 16px;
	}
	.form-signin .form-control:focus {
	  z-index: 2;
	}
	.form-signin input[type="text"] {
	  margin-bottom: -1px;
	  border-bottom-right-radius: 0;
	  border-bottom-left-radius: 0;
	}
	.form-signin input[type="password"] {
	  margin-bottom: 10px;
	  border-top-left-radius: 0;
	  border-top-right-radius: 0;
	}
	</style>

  </head>

  <body>

    <div class="container">
	<?php

    //apabila tombol login di klik akan menjalankan skript dibawah ini
	if( isset( $_REQUEST['login'] ) ){

        //mendeklarasikan data yang akan dimasukkan ke dalam database
		$username = $_REQUEST['admin'];
		$password = $_REQUEST['1'];

        //skript query ke insert data ke dalam database
		$sql = mysqli_query($koneksi, "SELECT id_user, username, nama, level FROM user WHERE username='$username' AND password=MD5('$password')");

        //jika skript query benar maka akan membuat session
		if( $sql){
			list($id_user, $username, $nama, $level) = mysqli_fetch_array($sql);

            //membuat session
            $_SESSION['id_user'] = $id_user;
			$_SESSION['username'] = $username;
			$_SESSION['nama'] = $nama;
			$_SESSION['level'] = $level;
			$password = $_REQUEST['password'];
			header("Location: ./admin.php");
			die();
		} else {

			$_SESSION['err'] = '<strong>ERROR!</strong> Username dan Password tidak ditemukan.';
			header('Location: ./');
			die();
		}

	} else {
	?>
      <form class="form-signin" method="post" action="" role="form">
		<?php
		if(isset($_SESSION['err'])){
			$err = $_SESSION['err'];
			echo '<div class="alert alert-warning alert-message">'.$err.'</div>';
            unset($_SESSION['err']);
		}
		?>
        <h2 class="form-signin-heading">Login Admin</h2>
        <input type="text" name="username" class="form-control" placeholder="Username" required autofocus>
        <input type="password" name="password" class="form-control" placeholder="Password" required>
        <button class="btn btn-lg btn-primary btn-block" type="submit" name="login">Login</button>
      </form>
	<?php
	}
	?>
    </div> <!-- /container -->

	<!-- Bootstrap core JavaScript, Placed at the end of the document so the pages load faster -->
    <script src="js/jquery.min.js"></script>
    <script src="js/bootstrap.min.js"></script>

	<script type="text/javascript">
		$(".alert-message").alert().delay(3000).slideUp('slow');
	</script>
  </body>
</html>