Csharp/C Sharp/Database ADO.net/XML Database

causes the the child rows to be nested within the parent rows in the output XML

 
using System;
using System.Data;
using System.Data.SqlClient;
class NestedXml {
    public static void Main() {
        SqlConnection mySqlConnection = new SqlConnection("server=localhost;database=Northwind;uid=sa;pwd=sa");
        SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
        mySqlCommand.rumandText =
          "SELECT TOP 2 CustomerID, CompanyName " +
          "FROM Customers " +
          "ORDER BY CustomerID;" +
          "SELECT OrderID, CustomerID, ShipCountry " +
          "FROM Orders " +
          "WHERE CustomerID IN (" +
          "  SELECT TOP 2 CustomerID " +
          "  FROM Customers " +
          "  ORDER BY CustomerID " +
          ")";
        SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter();
        mySqlDataAdapter.SelectCommand = mySqlCommand;
        DataSet myDataSet = new DataSet();
        mySqlConnection.Open();
        int numberOfRows = mySqlDataAdapter.Fill(myDataSet);
        Console.WriteLine("numberOfRows = " + numberOfRows);
        mySqlConnection.Close();
        DataTable customersDT = myDataSet.Tables["Table"];
        DataTable ordersDT = myDataSet.Tables["Table1"];
        DataRelation customersOrdersDataRel =
          new DataRelation(
            "CustomersOrders",
            customersDT.Columns["CustomerID"],
            ordersDT.Columns["CustomerID"]
          );
        myDataSet.Relations.Add(
          customersOrdersDataRel
        );
        myDataSet.WriteXml("nonNestedXmlFile.xml");
        myDataSet.Relations["CustomersOrders"].Nested = true;
        myDataSet.WriteXml("nestedXmlFile.xml");
    }
}

Fill data in DateSet to XmlDocument

 
using System;
using System.Data;
using System.Data.SqlClient;
using System.Xml;
class UsingXmlDocument {
    public static void Main() {
        SqlConnection mySqlConnection =
          new SqlConnection(
            "server=localhost;database=Northwind;uid=sa;pwd=sa"
          );
        SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
        mySqlCommand.rumandText =
          "SELECT TOP 2 CustomerID, CompanyName, Country " +
          "FROM Customers " +
          "ORDER BY CustomerID";
        SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter();
        mySqlDataAdapter.SelectCommand = mySqlCommand;
        DataSet myDataSet = new DataSet();
        mySqlConnection.Open();
        mySqlDataAdapter.Fill(myDataSet, "Customers");
        mySqlConnection.Close();
        XmlDocument myXmlDocument = new XmlDocument();
        myXmlDocument.LoadXml(myDataSet.GetXml());
        Console.WriteLine("Contents of myXmlDocument:");
        myXmlDocument.Save(Console.Out);
        foreach (XmlNode myXmlNode in myXmlDocument.SelectNodes("/NewDataSet/Customers")) {
            Console.WriteLine("CustomerID = " + myXmlNode.ChildNodes[0].InnerText);
            Console.WriteLine("CompanyName = " + myXmlNode.ChildNodes[1].InnerText);
            Console.WriteLine("Country = " + myXmlNode.ChildNodes[2].InnerText);
        }
        XmlNode myXmlNode2 = myXmlDocument.SelectSingleNode("/NewDataSet/Customers[CustomerID=\" ANATR\"]");
        Console.WriteLine("CustomerID = " + myXmlNode2.ChildNodes[0].InnerText);
        Console.WriteLine("CompanyName = " + myXmlNode2.ChildNodes[1].InnerText);
        Console.WriteLine("Country = " + myXmlNode2.ChildNodes[2].InnerText);
    }
}

illustrates how to write and read XML files

/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/

/*
  Example23_8.cs illustrates how to write and read XML files
*/
using System;
using System.Data;
using System.Data.SqlClient;
public class Example23_8
{
  public static void Main()
  {
    // formulate a string containing the details of the
    // database connection
    string connectionString =
      "server=localhost;database=Northwind;uid=sa;pwd=sa";
    // create a SqlConnection object to connect to the
    // database, passing the connection string to the constructor
    SqlConnection mySqlConnection =
      new SqlConnection(connectionString);
    // formulate a SELECT statement to retrieve the
    // CustomerID, CompanyName, ContactName, and Address
    // columns for the first two rows from the Customers table
    string selectString =
      "SELECT CustomerID, CompanyName, ContactName, Address " +
      "FROM Customers " +
      "WHERE CustomerID IN ("ALFKI", "ANATR")";
    // create a SqlCommand object to hold the SELECT statement
    SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
    // set the CommandText property of the SqlCommand object to
    // the SELECT string
    mySqlCommand.rumandText = selectString;
    // create a SqlDataAdapter object
    SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter();
    // set the SelectCommand property of the SqlAdapter object
    // to the SqlCommand object
    mySqlDataAdapter.SelectCommand = mySqlCommand;
    // create a DataSet object to store the results of
    // the SELECT statement
    DataSet myDataSet = new DataSet();
    // open the database connection using the
    // Open() method of the SqlConnection object
    mySqlConnection.Open();
    // use the Fill() method of the SqlDataAdapter object to
    // retrieve the rows from the table, storing the rows locally
    // in a DataTable of the DataSet object
    Console.WriteLine("Retrieving rows from the Customers table");
    mySqlDataAdapter.Fill(myDataSet, "Customers");
    // get the DataTable object from the DataSet object
    DataTable myDataTable = myDataSet.Tables["Customers"];
    // use the WriteXml() method to write the DataSet out to an
    // XML file
    Console.WriteLine("Writing rows out to an XML file named " +
      "myXmlFile.xml");
    myDataSet.WriteXml("myXmlFile.xml");
    // use the WriteXmlSchema() method to write the schema of the
    // DataSet out to an XML file
    Console.WriteLine("Writing schema out to an XML file named " +
      "myXmlSchemaFile.xml");
    myDataSet.WriteXmlSchema("myXmlSchemaFile.xml");
    // use the Clear() method to clear the current rows in the DataSet
    myDataSet.Clear();
    // use the ReadXml() method to read the contents of the XML file
    // into the DataSet
    myDataSet.ReadXml("myXmlFile.xml");
    // display the columns for each row in the DataTable,
    // using a DataRow object to access each row in the DataTable
    foreach (DataRow myDataRow in myDataTable.Rows)
    {
      Console.WriteLine("CustomerID = " + myDataRow["CustomerID"]);
      Console.WriteLine("CompanyName = " + myDataRow["CompanyName"]);
      Console.WriteLine("ContactName = " + myDataRow["ContactName"]);
      Console.WriteLine("Address = " + myDataRow["Address"]);
    }
    // close the database connection using the Close() method
    // of the SqlConnection object
    mySqlConnection.Close();
  }
}

Obtain an XML Document from a SQL Server Query

 
using System;
using System.Xml;
using System.Data;
using System.Data.SqlClient;
public class XmlQueryExample {
    public static void Main() {
        using (SqlConnection con = new SqlConnection()) {
            con.ConnectionString = "Data Source = localhost;" + 
                "Database = Northwind; Integrated Security=SSPI";
            SqlCommand com = con.CreateCommand();
            com.rumandType = CommandType.Text;
            com.rumandText = "SELECT CustomerID, CompanyName" + 
                " FROM Customers FOR XML AUTO";
            XmlReader reader = null;
            try {
                con.Open();
                reader = com.ExecuteXmlReader();
                while (reader.Read()) {
                    Console.Write(reader.Name);
                    if (reader.HasAttributes) {
                        for (int i = 0; i < reader.AttributeCount; i++) {
                            reader.MoveToAttribute(i);
                            Console.Write("  {0}: {1}",reader.Name, reader.Value);
                        }
                        reader.MoveToElement();  
                    }
                }
            } catch (Exception ex) {
                Console.WriteLine(ex.ToString());
            } finally {
                if (reader != null) reader.Close();
            }
        }
    }
}

Persisting A Dataset To An XML File

/*
 * C# Programmers Pocket Consultant
 * Author: Gregory S. MacBeth
 * Email: gmacbeth@comporium.net
 * Create Date: June 27, 2003
 * Last Modified Date:
 * Version: 1
 */
using System;
using System.Data;
using System.Data.OleDb;
namespace Client.Chapter_13___ADO.NET
{
    public class PersistingADatasetToAnXMLFile
    {
        static void Main(string[] args)
        {
            OleDbConnection MyConnection = new OleDbConnection(@"Provider=Microsft.Jet.OLEDB.4.0; Data Source = c:\MyAccessDB.mdb");
            OleDbDataAdapter MyAdapter = new OleDbDataAdapter("SELECT Column1, Column2, Column3 FROM MyTable", MyConnection);
            DataSet MyDataSet = new DataSet();
            MyAdapter.Fill(MyDataSet, "MyTable");
            MyDataSet.WriteXml(@"c:\MyDatSet.xml");
        }
    }
}

Reading An XML File Into A Dataset

/*
 * C# Programmers Pocket Consultant
 * Author: Gregory S. MacBeth
 * Email: gmacbeth@comporium.net
 * Create Date: June 27, 2003
 * Last Modified Date:
 * Version: 1
 */
using System;
using System.IO;
using System.Data;

namespace Client.Chapter_13___ADO.NET
{
    public class ReadingAnXMLFileIntoADataset
    {
        static void Main(string[] args)
        {
            string MyXMLDoc = @"<?xml version="1.0">?
                            <title> MyExample</title>";
            StringReader MyStringReader = new StringReader(MyXMLDoc);
            DataSet MyDataSet = new DataSet();
            MyDataSet.ReadXml(MyStringReader);
        }
    }
}