# Checks if some changes can be done or not, without actually
bool could_do_changes() {
  Database d = connect();
  defer { d.disconnect(); }

  inserted_row = d.insert("some", "row");
  defer { d.delete(inserted_row); }

  if (somecheck) return false;

  rows_to_update = d.query("oldvalue");
  d.update(rows_to_update, "newvalue");
  defer { d.update(rows_to_update, "oldvalue"); }

  if (somecheck) return false;

  to_delete = d.query("to_delete")
  d.delete(to_delete)
  defer { d.insert(to_delete); }

  return true;
}