$username= $_SESSION['validuser'];
  $result = mysql_query("SELECT * FROM user WHERE username= '$username' AND passwd = PASSWORD('$passwdold')");
  //Check for database error
  //dberror($result);

 //If result is found, true otherwise password is wrong
  if (mysql_num_rows($result)>0)
   {
   }
   else
   {
   header('Location: myaccount.php?errcode=15');
   exit;
   }