将数据库读取的表写入xml时出现错误！求帮帮看下~

Question

public static void create_xml(string sql, string top_node, string xml_filename)
    {
      String se = System.AppDomain.CurrentDomain.BaseDirectory;
        string consql = ConfigurationSettings.AppSettings["consql"].ToString();
        SqlConnection con = new SqlConnection(consql);
        con.Open();
        SqlCommand cmd = new SqlCommand(sql,con);
        System.Xml.XmlTextReader rd;
        rd = (System.Xml.XmlTextReader)cmd.ExecuteXmlReader();
        System.IO.StreamWriter w = new System.IO.StreamWriter(xml_filename, false, System.Text.Encoding.GetEncoding("gb2312"));
        w.WriteLine("<?xml version='1.0'encoding='gb2312'?>");
        w.WriteLine("<"+top_node+">");
        while (rd.IsStartElement()) 
            w.WriteLine(rd.ReadOuterXml());
            w.WriteLine("</"+top_node+">");
            w.Close();
            rd.Close();
            con.Close();
    }

下面是调用方法的代码

 protected void Button5_Click(object sender, EventArgs e)
    {
        string xml = TextBox5.Text;
        string gen = "stundet";
        stat.create_xml("select stor_id,stor_name,stor_address from stores for xml auto",gen,Server.MapPath(""+xml+".xml"));
    }

 

运行后出现这样错误

无法将类型为“System.Xml.XmlTextReaderImpl”的对象强制转换为类型“System.Xml.XmlTextReader”。

请问应该如何改这个错误呢？？？

Answer 1

System.Xml.XmlTextReader rd; rd = (System.Xml.XmlTextReader)cmd.ExecuteXmlReader(); 这个地方把XmlTextReader 改成  System.Xml.XmlReader rd; rd = cmd.ExecuteXmlReader();

Answer 2

这样写很麻烦，你可以试用一下LINQ那样产生XML非常的简单