function add_bm($new_url)
{
  // Add new bookmark to the database

  echo "Attempting to add ".htmlspecialchars($new_url).'<br />';
  global $HTTP_SESSION_VARS;
  $valid_user = $HTTP_SESSION_VARS['valid_user'];
  
  if (!($conn = db_connect()))
    return false;

  // check not a repeat bookmark
  $result = mysql_query("select * from bookmark
                         where username='$valid_user' 
                         and bm_URL='$new_url'");
  if ($result && (mysql_num_rows($result)>0))
    return false;

  // insert the new bookmark
  if (!mysql_query( "insert into bookmark values
                          ('$valid_user', '$new_url')"))
    return false; 

  return true;
}