title: how to prevent user multiple login with single account
body: <p>i need help to completed my login script and but i'm confused how to prevent user multiple login with single account?</p>
  
  <p>in my website i have membership subscription one is free and another is one paid but i want to create more secure login system and also i want embed this function that paid user can't be login from multiple pc or browser once user already logged from single account.</p>
  
  <p><strong>Example Of System</strong> </p>
  
  <pre><code>1)if user login from google chrome and trying to login from firfox then system should automtically destroy      chrome session? 
  </code></pre>
  
  <p><strong>Here My Login Script</strong></p>
  
  <pre><code>$email=$_POST['email'];
  $password=$_POST['password'];
  $email = stripslashes($email);
  $password= stripslashes($password);
  $email = mysql_real_escape_string($email);
  $password = mysql_real_escape_string($password);
  
  
  //selecting user from db
  $querymysql=mysql_query("select * from students where semail='$email'
  and spassword='$password'") or die ("query problem");
  
  $row=mysql_fetch_array($querymysql);
  $name=$row['sname'];
  $act=$row['activation'];
  $e=$row['semail'];
  $p=$row['spassword'];
  $ss=$row['sstatus'];
  
  if($row&gt;0){
  
  if($row['sstatus']=="allow")
  {   
  if($row["activation"]=="activated")
  {
  
  $_SESSION['logclass']=$row['sclass'];
  $_SESSION['logname']=$row['sname'];
  $_SESSION['logsid']=$row['sid'];        
  $_SESSION['logemail']=$row['semail'];   
  $_SESSION['logclass']=$row['sclass'];
  $_SESSION['logsubscribe']=$row['subscribe'];
  
  
  $_SESSION['logged']=$row['loginstatus'];
  
  $_SESSION['logged_in'] = true;
  
  if(isset($_SESSION['logged_in']))
  {
  $query_time=mysql_query("UPDATE students SET loginstatus='".$_SESSION['logged_in']."'
  WHERE semail='".$email."'");
  header('Location:users/dashboard/index.php');
  }
  
  }
  if($login1==$_SESSION['logged_in'])
  {
  header("location:logout.php");  
  }
  
  
  }else if ($row["activation"]!="activated")
  {
  $actmsg="text"; 
  header('Location:login.php?actmsg='.$actmsg.'');
  }
  }
  else 
  {
  $pending="Your Account Is Not Approved By Admin";   
  header('Location:login.php?pending='.$pending.'');  
  }
  }
  
  else
  {
  $message="Please Check Your Login Details"; 
  header('Location:login.php?login_error='.$message.'');  
  }
  </code></pre>