ASP.net Xml: DataSet的ReadXml(), WriteXml()和Response写Xml文档

using System;

using System.Data;
using System.Data.SqlClient;
public partial class DemoWriteXml : System.Web.UI.Page
{

    /// <summary>
    /// ylb:1,把数据库中的表写成XML文档
    /// 数据读取器(DataReader)
    /// </summary>
    private void WriteXml()
    {
        string sql = "select top 10 productID,productName,unitPrice from Products";
        //string connStr = "Server=.;Database=Northwind;uid=sa;pwd=m123";
        string connStr = "Server=.;Database=Northwind;Integrated Security=SSPI";

        //创建一个虚拟库
        DataSet ds = new DataSet("Northwind");
        //创建一个虚拟表
        DataTable dt = new DataTable("Products");

        SqlConnection conn = new SqlConnection(connStr);
        SqlCommand com = conn.CreateCommand();

        //把sql赋值给com.CommandText
        com.CommandText = sql;
        //peican

        conn.Open();

        //execute
        try
        {
            SqlDataReader sdr = com.ExecuteReader();

            //向虚拟表中加载数据
            dt.Load(sdr);
        }
        finally
        {
            conn.Close();
        }

        //把表添加到库中 
        ds.Tables.Add(dt);

        //写XML文档
        ds.WriteXml(Server.MapPath("Products.xml"));

        Response.Write("写Xml文档成功！");

    }

    
    /// <summary>
    /// ylb:2,把数据库中的表写成XML文档
    /// 用适配器(DataAdapter)
    /// </summary>
    private void WriteXml2()
    {
        string sql = "select top 10 productID,productName,unitPrice from Products";
        string connStr = "Server=.;Database=Northwind;Integrated Security=SSPI";

        //创建一个虚拟表
        DataSet ds = new DataSet("Northwind");

        SqlDataAdapter sdr = new SqlDataAdapter(sql, connStr);

        //用适配器去填充虚拟库
        sdr.Fill(ds);

        ds.Tables[0].TableName = "Products";    //给表格命名        

        //写XML文档
        ds.WriteXml(Server.MapPath("Products2.xml"));

        Response.Write("写Xml文档成功！");
    }

    /// <summary>
    /// ylb:2,把数据库中的表写成XML文档
    /// 用适配器(DataReader)
    /// </summary>
    private void WriteXml3()
    {
        string connStr = "Server=.;Database=Northwind;Integrated Security=SSPI";
        string sql = "select top 10 productId,productName,unitprice from products";


        SqlConnection conn = new SqlConnection();
        conn.ConnectionString = connStr;

        SqlCommand cmd = conn.CreateCommand();
        cmd.CommandText = sql;

        conn.Open();
        try
        {
            //直接输出Xml文档
            Response.ContentType = "text/xml";  //输出文档类型为xml
            Response.Write("<?xml version='1.0' encoding='UTF-8'?>");   //声明xml
            Response.Write("<Northwind>");   //起始根元素
            SqlDataReader sdr = cmd.ExecuteReader();
            while (sdr.Read())
            {
                //子元素
                Response.Write("<Products>");
                Response.Write(string.Format("<productId>{0}</productId>", sdr.GetInt32(0)));
                Response.Write(string.Format("<productName>{0}</productName>", sdr.GetString(1)));
                Response.Write(string.Format("<unitprice>{0}</unitprice>", sdr.GetDecimal(2)));
                Response.Write("</Products>");
            }
            Response.Write("</Northwind>"); //终止根元素

        }
        finally
        {
            conn.Close();
        }

        Response.End(); //停止前台页面输出
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        //调用
        //ylb:1,
        //WriteXml();

        //ylb:2,
        //WriteXml2();

        //ylb:3,
        WriteXml3();
    }
}