//使用XMLWriter写XML数据            XmlWriterSettings settings = new XmlWriterSettings();            settings.Indent = true; //缩进            //settings.NewLineOnAttributes = true; //属性换新的一行            XmlWriter writer = XmlWriter.Create("Books.xml", settings);//创建XmlWriter实例            writer.WriteStartDocument();//XML文档声明            writer.WriteStartElement("book"); //开始标记 1            writer.WriteAttributeString("Type","科幻");//添加属性            writer.WriteAttributeString("ISBN", "001-001-001");//添加属性            writer.WriteElementString("title", "名侦探柯南");//添加元素            writer.WriteElementString("price", "99.99");//添加元素            writer.WriteStartElement("author");//开始标记 2            writer.WriteElementString("name", "谁谁谁");//添加元素            writer.WriteEndElement();//结束标记 2            writer.WriteEndElement();//结束标记 1            writer.WriteEndDocument(); //关闭所有文档标记            writer.Flush(); //刷新流            writer.Close(); //关闭流                    

<?xml version="1.0" encoding="utf-8"?><book Type="科幻" ISBN="001-001-001">  <title>名侦探柯南</title>  <price>99.99</price>  <author>    <name>谁谁谁</name>  </author></book>

<?xml version="1.0" encoding="utf-8"?><book Type="科幻" ISBN="001-001-001">  <title>哈利波特</title>  <price>99.99</price>  <author>    <name>JK罗琳</name>  </author></book><book Type="青春" ISBN="001-001-002">  <title>左耳</title>  <price>9.99</price>  <author>    <name>饶雪漫</name>  </author></book><book Type="悬疑" ISBN="001-001-003">  <title>盗墓笔记</title>  <price>99.99</price>  <author>    <name>南派三叔</name>  </author></book>

            XmlDocument doc = new XmlDocument();            doc.Load("D:\\Books.xml");//加载XML文档，文件必须存在且有根元素            //创建一个节点            XmlElement newbook = doc.CreateElement("book");            //设置属性            newbook.SetAttribute("type", "story");            newbook.SetAttribute("publishdate", "1993");            newbook.SetAttribute("ISBN", "002-123-321");            //设置元素            XmlElement name = doc.CreateElement("Name");            name.InnerText = "I have a Dream";            newbook.AppendChild(name);            XmlElement price = doc.CreateElement("Price");            price.InnerText = "9.99";            newbook.AppendChild(price);            //添加到节点            doc.DocumentElement.AppendChild(newbook);            //写入磁盘（追加）            XmlTextWriter tr = new XmlTextWriter("D:\\Books.xml", null);            tr.Formatting = Formatting.Indented;//设置缩进格式            doc.WriteContentTo(tr);//保存 写入            tr.Close();        

<?xml version="1.0" encoding="utf-8"?><Books>  <book type="story" publishdate="1993" ISBN="002-123-321">    <Name>I have a Dream</Name>    <Price>9.99</Price>  </book></Books>

<?xml version="1.0" encoding="utf-8"?><bookstore>    <book Type="科幻" ISBN="001-001-001">      <title>哈利波特</title>      <price>99.99</price>      <author>        <name>JK罗琳</name>      </author>    </book>    <book Type="青春" ISBN="001-001-002">      <title>左耳</title>      <price>9.99</price>      <author>        <name>饶雪漫</name>      </author>    </book>    <book Type="悬疑" ISBN="001-001-003">      <title>盗墓笔记</title>      <price>99.99</price>      <author>        <name>南派三叔</name>      </author>    </book></bookstore>

            XmlDocument doc = new XmlDocument();            doc.Load("D:\\Books.xml");            //输出所有节点为Name的元素            //1.            XmlNodeList nodelist = doc.GetElementsByTagName("title");            //2.使用XPath语法从文档中检索一组节点            //XmlNodeList nodelist = doc.SelectNodes("/bookstore/book/title");            foreach (XmlNode node in nodelist)            {                richTextBox1.AppendText(node.InnerXml + "\r\n");            }

　　　　using System.Data;　　　　using System.Xml;　　　　using System.Data.SqlClient;　　　　using System.Xml.Linq;            string connString = "server=服务器名;database=数据库;uid=账户;pwd=密码";            ///ADO.NET数据转换XML文档            //1:创建一个ADO.NET对象，生成一个DataSet对象            SqlConnection conn = new SqlConnection(connString);            SqlDataAdapter dataAdapter1 = new SqlDataAdapter("select Barcode from Books", conn);            DataSet dataSet1 = new DataSet();            dataAdapter1.Fill(dataSet1, "BooksBarCode");            //2:把XML文档存到磁盘中(覆盖数据)            string file = @"C:\Users\WIN20150720\Desktop\Books.xml";            dataSet1.WriteXml(file);            ///XML文档转换ADO.NET数据            //1:创建DataSet对象            DataSet dataSet2 = new DataSet();            //2:读取XML文档            dataSet2.ReadXml(file);            //3:绑定到网格            dataGridView1.DataSource = dataSet2.Tables[0];            ///SQL从数据库查询            //根据BarCode获取全部信息            string barcode = "";            foreach (DataRow dr in dataSet2.Tables[0].Rows)            {                barcode += dr["Barcode"].ToString() + ",";            }            barcode = barcode.Substring(0, barcode.LastIndexOf(","));            string sql = string.Format("Select * from Books where BarCode in({0})", barcode);            SqlDataAdapter dataAdapter2 = new SqlDataAdapter(sql, conn);            DataSet dataSet3 = new DataSet();            dataAdapter2.Fill(dataSet3, "BooksInfo");            string file2 = @"C:\Users\WIN20150720\Desktop\AllBooks.xml";            dataSet3.WriteXml(file2);

<?xml version="1.0" encoding="utf-8" ?><Data>  <Products>    <Product Name="West Side Story" Price="9.99m" SuppelierID="1"/>    <Product Name="Assassins" Price="14.99m" SuppelierID="2"/>    <Product Name="Frogs" Price="13.99m" SuppelierID="1"/>    <Product Name="Sweeney Todd" Price="9.99m" SuppelierID="3"/>  </Products>  <Suppliers>    <Supplier Name="Solely Sondheim" SupplierID="1"/>    <Supplier Name="CD-by-CD-by-Sondheim" SupplierID="2"/>    <Supplier Name="Barbershop CDs" SupplierID="3"/>  </Suppliers></Data>

using System.Xml.Linq;namespace ConsoleApplication1{    class XML_LINQ    {        static void Main()        {            //将产品和供货商连接起来，价格高于10美元，先按供货商名排序，在按产品名排序，最后打印供货商名和产品名            //供货商和产品编码使用XML文件            XDocument doc = XDocument.Load("data.xml");    //XDocument使用命名空间System.Xml.Linq;            var filtered = from p in doc.Descendants("Product")                            join s in doc.Descendants("Supplier")                            on (int)p.Attribute("SupplierID")                            equals (int)s.Attribute("SupplierID")                            where (decimal)p.Attribute("Price") > 10                            orderby (string)s.Attribute("Name"), (string)p.Attribute("Name")                            select new                            {                                SupplierName = (string)s.Attribute("Name"),                                ProductName = (string)s.Attribute("Name")                            };            foreach (var v in filtered)            {                Console.WriteLine("Supplier={0};Product={1}", v.SupplierName, v.ProductName);            }        }    }}

<?xml version="1.0" encoding="utf-8"?><bookstore>    <book Type="科幻" ISBN="001-001-001">      <title>哈利波特</title>      <price>99.99</price>      <author>        <name>JK罗琳</name>      </author>    </book>    <book Type="青春" ISBN="001-001-002">      <title>左耳</title>      <price>9.99</price>      <author>        <name>饶雪漫</name>      </author>    </book>    <book Type="悬疑" ISBN="001-001-003">      <title>盗墓笔记</title>      <price>99.99</price>      <author>        <name>南派三叔</name>      </author>    </book></bookstore>

　　　　　　　//根据书名查找价格和作者            
　　　　　　　XDocument doc = XDocument.Load("D:\\Books.xml");            var query = from p in doc.Element("bookstore").Elements("book")                        where (string)p.Element("title") == "左耳"                        select p;            query.ToList().ForEach(item =>            {                decimal price = (decimal)item.Element("price");                 string author = item.Element("author").Value;            });

            //查找所有的书名            XDocument xdoc = XDocument.Load("D:\\Books.xml");            var query = from title in xdoc.Descendants("title")                        select title.Value;            foreach (var item in query)            {                richTextBox1.AppendText(item + "\r\n");            }