<?php

if (!$_SESSION["valid_user"]) {
       // User not logged in, redirect to login page
      Header("Location: login.php");
}
else
{
echo "SELECT * FROM users where username='$username' AND  password='$password' ";
$result = mysql_query("SELECT * FROM users WHERE username='".$_SESSION['username']."'");
$row = mysql_fetch_array($result);
$userid = $row['user_id'];

}
?>