title: On clicking back button, I'm still on the same page that has the form
body: <p>I'm a beginner in making a website and I'm still practising in making a website using PHP lounge. </p>
  
  <p>This is the problem that I'm facing, if I click back button I'm still on the login page, how can i remove login form?</p>
  
  <p><a href="http://i.stack.imgur.com/M5LRB.png" rel="nofollow">Here is the image</a></p>
  
  <p><strong>my php code for login from my database</strong>
      
  
  <pre><code>    $member_email = $_POST["member_email"];
      $member_password = md5($_POST["member_password"]);
  
      require_once("db_open.php");
      $sql = "SELECT * FROM members WHERE member_email='".$member_email."' AND member_password='".$member_password."'";
      $result = $conn-&gt;query($sql) or die($conn-&gt;error);
      if ($result-&gt;num_rows &gt; 0) {
          while($row = $result-&gt;fetch_assoc()) {
              session_start();
              $_SESSION["member_id"] = $row["member_id"];
              $_SESSION["member_email"] = $row["member_email"];
              $_SESSION["member_full_name"] = $row["member_full_name"];
          }
      } else {
          header("Location: login_form.php");
          exit();
      }
      require_once("db_close.php");
  
      header("Location: index.php");
  
  ?&gt;
  </code></pre>
  
  <p><strong>Code for my checking for my login</strong> </p>
  
  <pre><code>&lt;?php
  
      if (!isset($_SESSION["member_id"])) {
          exit("&lt;h3&gt;Please &lt;a class='btn btn-primary' href='login_form.php'&gt;login&lt;/a&gt; first.&lt;/h3&gt;");
      }
  
  ?&gt;
  </code></pre>
  
  <p><strong>Here is my html and login form</strong></p>
  
  <pre><code>&lt;?php
      session_start();
  ?&gt;
  
  &lt;!DOCTYPE html&gt;
  
  &lt;html&gt;
  
  
  &lt;head&gt;
      &lt;title&gt;All Members&lt;/title&gt;
      &lt;link rel="stylesheet" href="bootstrap.min.css" /&gt;
  &lt;/head&gt;
  
  
  &lt;body&gt;
  
  &lt;?php require_once("top_nav.php"); ?&gt;
  
  &lt;div class="container"&gt;
  
      &lt;h1&gt;Login&lt;/h1&gt;
  
      &lt;form method="POST" action="login_db.php"&gt;
          &lt;div class="form-group"&gt;
              &lt;label for="member_email"&gt;Email:&lt;/label&gt;
              &lt;input type="text" name="member_email" id="member_email" class="form-control" /&gt;
          &lt;/div&gt;
          &lt;div class="form-group"&gt;
              &lt;label for="member_password"&gt;Password:&lt;/label&gt;
              &lt;input type="password" name="member_password" id="member_password" class="form-control" /&gt;
          &lt;/div&gt;
          &lt;button type="submit" class="btn btn-success btn-lg"&gt;Login&lt;/button&gt;
      &lt;/form&gt;
  &lt;/div&gt;
  
  &lt;/body&gt;
  
  
  &lt;/html&gt;
  </code></pre>