Java关于数据库查询的一些问题

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当同时查询多个数据集合时，需要定义多个statement，因为每个若同时使用一个statement，那么数据会不断进行覆盖。

while(rs.next()) {
                cnt++;
                String provinceid = rs.getString("provinceId");
                String provinceName = rs.getString("provinceName");
                String sql2 = "select * from tcity where provinceId="+provinceid;
                ResultSet rs2 = stat2.executeQuery(sql2);
                out.println("<tr>");
                out.println("<th colspan = \"2\" id = \"firstrow\">"+provinceName+"</th>");
                out.println("</tr>");
                out.println("<tr>");
                out.println("<th>邮政编码</th>");
                out.println("<th>城市名称</th>");
                out.println("</tr>");
                while(rs2.next()) {
                    String cityName = rs2.getString("cityName");
                    String cityCode = rs2.getString("cityCode");
                    out.println("<tr>");
                    out.println("<th>"+cityCode+"</th>");
                    out.println("<th>"+cityName+"</th>");
                    out.println("</tr>");
                  //  out.print(provinceName+" "+city);
                  //  out.print("<br>");
                }

            }
        out.println("</table>");