DataSet里的数据写入XML文件

//连接字符串
string strConn = @"Data Source=192.168.1.9;password=sa;user id= sa;Initial Catalog =cityfamily";

//用于取数据的sql语句
//注意：在sql语句里给字段重新命名了，当然也可以不对其重新命名
string sqlStr = "select msg_date as date,msg_user as name,msg_admin as isadmin,msg_content as content,msg_comment as comment from user_message where msg_scene ='001'";
SqlConnection sqlConn = new SqlConnection(strConn);
sqlConn.Open();
DataSet ds = new DataSet();
SqlCommand sqlCmd = new SqlCommand(sqlStr, sqlConn);
sqlCmd.ExecuteNonQuery();
SqlDataAdapter sqlAdapter = new SqlDataAdapter(sqlCmd);
sqlAdapter.Fill(ds, "msg");//添充dataset时，对其表名重新命名，当然也可以不对其重新命名

ds.Tables["msg"].Columns["name"].ColumnMapping = MappingType.Attribute;//把某一列做为属性的操作
ds.Tables["msg"].Columns["date"].ColumnMapping = MappingType.Attribute;//把某一列做为属性的操作
ds.Tables["msg"].Columns["isadmin"].ColumnMapping = MappingType.Attribute;//把某一列做为属性的操作
//ds.Tables["city_users"].Columns["user_pwd"].ColumnMapping = MappingType.Attribute;//把某一列做为属性的操作

XmlTextWriter xtw = new XmlTextWriter("x.xml", Encoding.GetEncoding("utf-8"));
xtw.WriteRaw("<?xml version=\"1.0\" encoding=\"utf-8\"?>");//手动写入原始标记

//for (int i = 0; i < ds.Tables["city_users"].Rows.Count;i++ )
ds.DataSetName = "mapmsg";//这里改了dataSet对像的名称，对应了XML文档的根结点
ds.WriteXml(xtw);

xtw.Close();
sqlConn.Close();