$previous_database = db_set_active('seperate_db')
db_set_active($previous_database);

function swap_db_form_alter($form_id, &$form) {

  // Send profile data to external database.

  if (isset($form['type']) && 'user-edit' == $form_id) {
    if (db_result(db_query("SELECT fid FROM {profile_fields} WHERE username = '%s'". $query_suffix, $args2))) {

     $form['#submit']['send_to_db'] = array();

    }
  }
}


function send_to_db($user_profile, $mode) {

  $name = $user_profile->username;
  $user = db_fetch_object(db_query("
  SELECT uid 
  FROM {JOIN_TABLE_USERS} 
  WHERE exid = '%s'",
    $name
  ));
  
  if ($user) {

    $node->field_age[0]['value'] = $user_profile->age;
    $node->field_location[0]['value'] = $user_profile->location;

    $exists = db_fetch_object(db_query("
      SELECT nid
      FROM node n
      WHERE n.type = 'user_profile'
      AND n.uid = %d",
      $user->uid
    ));

  if ($exists) $node->nid = $exists->nid;

  if ($mode == 1) node_save($node);
  return $output;

}

db_set_active();