PHP：登录后用户点击后退按钮时如何防止用户进入登录页面？

Question

Basically, i dont want the user accessibly to the login page by clicking back button after he/she successfully login to the system.

Below us the code of login check.php:-

<?php


include 'database.php'; 
session_start();                                            

if (isset ($_POST['namaPengguna']))
{                   
$kataLaluan = $_POST['kataLaluan'];
$namaPengguna = $_POST['namaPengguna'];

$query = "SELECT * FROM pengguna 
        WHERE namaPengguna='$namaPengguna' && kataLaluan = '$kataLaluan' ";

$result = $mysqli->query($query) or die($mysqli->error._LINE_);
$row = $result->num_rows; 
$info = $result->fetch_assoc(); 
$_SESSION['PenggunanoKP']=$info['PenggunanoKP'];

    if($row<1)  
    {
       header("Location:login design.php");
    }
    else{
         header("Location:pilihAction.php");
    }

}

?>

The next page :

<?php include 'database.php';
include 'session.php'; 
?>


<?php

echo $_SESSION['PenggunanoKP'];
?>
/*html code

Answer 1

Your Welcome Page (after login) should look like this

<?php
  session_start();
  if(isset($_SESSION['directaccess']))
  {
    if(isset($_POST['logoutbtn']))
    {
        session_destroy();
        header("location: loginform.php");
    }
  /* Your code goes here */

  }
  else{
     exit('Access denied');
   }
  ?>

 <form class="myform" action="" method="post">  
 <input name="logoutbtn" type="submit" value="logout" class="sbbtn" 
  id="logout_btn" class="test"/>
 </form>
  </div>
 </body>
  </html>

Explanation : On your Main Login/check-in page : Set a flag in $_SESSION (in my example its $_SESSION['directaccess']) just before calling header function (to successful login Welcome page). . Then on your success Welcome Page, use the code snippet above. Check if that flag is set then only give access to your Page code else exit('Access Denied').

Logout button action should be on the same Welcome page. If button is clicked, destroy session and then call header function back to Main Login/check-in page.