public static void saveMail(User user, Message message) {

    ResultSet resultSet = null;

    try {

      String sql =
          "INSERT INTO mail (mailid,userid,hash,message) values("
              + message.getId()
              + ","
              + user.getId()
              + ",'"
              + message.getHash()
              + "','"
              + message.getContent()
              + "');";

      getStatement().execute(sql);

      resultSet.close();
      getStatement().close();

    } catch (SQLException e) {
      e.printStackTrace();
    }
  }
  public static void deleteMailById(Message message) {

    // precondition blablabla

    String sql = "DELETE FROM mail WHERE mailid = " + message.getId() + ";";
    try {
      getStatement().execute(sql);
      getStatement().close();
    } catch (SQLException e) {
      e.printStackTrace(); // To change body of catch statement use File | Settings | File
      // Templates.
    }
  }