Question

我使用预处理语句进行交叉表查询（使用postgres）我正在尝试添加一个参数（中心），但它不起作用我的代码：

  public List<openbookBean> summarylist(String center) throws SQLException {
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;

         String querystring = "select team_manager as team_manager2, "
                        + "compliance_1 as day1, "
                        + "compliance_2 as day2, "
                        + "compliance_3 as day3 "

                        + "FROM crosstab('select team_manager, date_compliance, compliance from openbook_comp where("
                        + "extract(day from date_compliance)= ''1'' or "
                        + "extract(day from date_compliance)= ''2'' or "
                        + "extract(day from date_compliance)= ''3'') "

                        + "and center = '''?''' "

                        + "order by 1,2') AS openbook_comp (team_manager text, "
                        + "compliance_1 varchar,"
                        + "compliance_2 varchar,"
                        + "compliance_3 varchar)";





        List<openbookBean> summarylist_array = new ArrayList<openbookBean>();

        try {

            connection = database.getConnection();
            statement = connection.prepareStatement(querystring);

                statement.setString(1, center);


            resultSet = statement.executeQuery();

            while (resultSet.next()) {
                openbookBean summarylistarray = new openbookBean();
                    summarylistarray.setTeam_manager2(resultSet.getString("team_manager2"));
                    summarylistarray.setDay1(resultSet.getString("day1"));
                    summarylistarray.setDay2(resultSet.getString("day2"));
                    summarylistarray.setDay3(resultSet.getString("day3"));


                summarylist_array.add(summarylistarray);
            }
        } finally {
            try { resultSet.close(); } catch (SQLException logOrIgnore) {}
            try { statement.close(); } catch (SQLException logOrIgnore) {}
            try { connection.close(); } catch (SQLException logOrIgnore) {}
        }

        return summarylist_array;
    }

    }

这是servlet的一部分

if (request.getParameter("show").equals("summary")) {
     try {
        List<openbookBean> summarylist_array = openbookDAO.summarylist(region);

        request.setAttribute("summarylist_array", summarylist_array);
        request.getRequestDispatcher("summary.jsp").forward(request, response);
    }

    catch (SQLException e) {
      throw new ServletException("Cannot retrieve areas", e);
    }

    }

我总是收到这个错误：

java.lang.NullPointerException
    source.openbookDAO.summarylist(openbookDAO.java:358)
    source.openbookServlet.doGet(openbookServlet.java:74)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

Answer 1

您没有关闭最后一个括号，还有一个额外的逗号：

            + "order by 1,2') AS openbook_comp (team_manager text, "
            + "compliance_1 varchar,"
            + "compliance_2 varchar,"
            + "compliance_3 varchar)"

你可以用这个：

            + "extract(day from date_compliance) in (1, 2, 3) "

如果center是数字，请不要使用引号并在参数后添加空格：

             + "and center = ? "

如果不是数字，请尝试这样：

            + "and center = '''?''' "

postgres交叉表参数

1 个答案: