public void doPost(HttpServletRequest request, 
    HttpServletResponse response) 
    throws ServletException, IOException {
    sendPageHeader(response);

    firstName = request.getParameter("firstName");
    lastName = request.getParameter("lastName");
    userName = request.getParameter("userName");
    password = request.getParameter("password");

    boolean error = false;
    String message = null;
    try {
      Connection con = DriverManager.getConnection("jdbc:odbc:JavaWeb");
      System.out.println("got connection");

      Statement s = con.createStatement();

      String sql = "SELECT UserName FROM Users" +
        " WHERE userName='" + StringUtil.fixSQLFieldValue(userName) + "'";
      ResultSet rs = s.executeQuery(sql);
      if (rs.next()) {
        rs.close();
        message = "The user name <B>" + StringUtil.encodeHtmlTag(userName) +
          "</B> has been taken. Please select another name.";
        error = true;
      }
      else {
        rs.close();
        sql = "INSERT INTO Users" +
          " (FirstName, LastName, UserName, Password)" +
          " VALUES" +
          " ('" +  StringUtil.fixSQLFieldValue(firstName) + "'," +
          " '" +  StringUtil.fixSQLFieldValue(lastName) + "'," +
          " '" +  StringUtil.fixSQLFieldValue(userName) + "'," +
          " '" +  StringUtil.fixSQLFieldValue(password) + "')";
        int i = s.executeUpdate(sql);
        if (i==1) {
          message = "Successfully added one user.";
        }
      }
      s.close();
      con.close();
    }
    catch (SQLException e) {
      message = "Error." + e.toString();
      error = true;
    }
    catch (Exception e) {
      message = "Error." + e.toString();
      error = true;
    }
    if (message!=null) {
      PrintWriter out = response.getWriter();
      out.println("<B>" + message + "</B><BR>");
      out.println("<HR><BR>");
    }
    if (error==true)
      sendRegistrationForm(request, response, true);
    else
      sendRegistrationForm(request, response, false);
    sendPageFooter(response);
  }