Csharp/C Sharp/Database ADO.net/DataRelation

More than one Relations

using System;
using System.Data;
using System.Data.SqlClient;
using System.Collections.Generic;
using System.Text;
class Program {
    static void Main(string[] args) {
        SqlConnection thisConnection = new SqlConnection(@"Server=(local)\sqlexpress;Integrated Security=True;" +
             "Database=northwind");
        DataSet thisDataSet = new DataSet();
        SqlDataAdapter custAdapter = new SqlDataAdapter("SELECT * FROM Customers", thisConnection);
        custAdapter.Fill(thisDataSet, "Customers");
        SqlDataAdapter orderAdapter = new SqlDataAdapter("SELECT * FROM Orders", thisConnection);
        orderAdapter.Fill(thisDataSet, "Orders");
        SqlDataAdapter detailAdapter = new SqlDataAdapter("SELECT * FROM [Order Details]", thisConnection);
        detailAdapter.Fill(thisDataSet, "Order Details");
        SqlDataAdapter prodAdapter = new SqlDataAdapter("SELECT * FROM Products", thisConnection);
        prodAdapter.Fill(thisDataSet, "Products");
        DataRelation custOrderRel = thisDataSet.Relations.Add("CustOrders",
                    thisDataSet.Tables["Customers"].Columns["CustomerID"],
                    thisDataSet.Tables["Orders"].Columns["CustomerID"]);
        DataRelation orderDetailRel = thisDataSet.Relations.Add("OrderDetail",
                    thisDataSet.Tables["Orders"].Columns["OrderID"],
                    thisDataSet.Tables["Order Details"].Columns["OrderID"]);
        DataRelation orderProductRel = thisDataSet.Relations.Add(
          "OrderProducts", thisDataSet.Tables["Products"].Columns["ProductID"],
           thisDataSet.Tables["Order Details"].Columns["ProductID"]);
        foreach (DataRow custRow in thisDataSet.Tables["Customers"].Rows) {
            Console.WriteLine("Customer ID: " + custRow["CustomerID"]);
            foreach (DataRow orderRow in custRow.GetChildRows(custOrderRel)) {
                Console.WriteLine("\tOrder ID: " + orderRow["OrderID"]);
                Console.WriteLine("\t\tOrder Date: " + orderRow["OrderDate"]);
                foreach (DataRow detailRow in
                         orderRow.GetChildRows(orderDetailRel)) {
                    Console.WriteLine("\t\tProduct: " +
                    detailRow.GetParentRow(orderProductRel)["ProductName"]);
                    Console.WriteLine("\t\tQuantity: " + detailRow["Quantity"]);
                }
            }
        }
        thisConnection.Close();
    }
}

Setting the Nested property of a DataRelation to true

using System;
using System.Data;
using System.Data.SqlClient;
class NestedXml
{
  public static void Main()
  {
    SqlConnection mySqlConnection =new SqlConnection("server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI;");
    SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
    mySqlCommand.rumandText =
      "SELECT TOP 2 EmployeeID, CompanyName " +
      "FROM Employee " +
      "ORDER BY EmployeeID;"  +
      "SELECT DeptID, EmployeeID, City " +
      "FROM Dept " +
      "WHERE EmployeeID IN (" +
      "  SELECT TOP 2 EmployeeID " +
      "  FROM Employee " +
      "  ORDER BY EmployeeID " +
      ")";
    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 customersDeptDataRel =
      new DataRelation(
        "EmployeeDept",
        customersDT.Columns["EmployeeID"],
        ordersDT.Columns["EmployeeID"]
      );
    myDataSet.Relations.Add(
      customersDeptDataRel
    );
    myDataSet.WriteXml("nonNestedXmlFile.xml");
    myDataSet.Relations["EmployeeDept"].Nested = true;
    myDataSet.WriteXml("nestedXmlFile.xml");
  }
}

Set up DataRelation

using System;
using System.Data;
using System.Data.SqlClient;
using System.Collections.Generic;
using System.Text;
class Program {
    static void Main(string[] args) {
        SqlConnection thisConnection = new SqlConnection(
             @"Server=(local)\sqlexpress;Integrated Security=True;" +
             "Database=northwind");
        SqlDataAdapter thisAdapter = new SqlDataAdapter(
             "SELECT CustomerID, CompanyName FROM Customers", thisConnection);
        SqlCommandBuilder thisBuilder = new SqlCommandBuilder(thisAdapter);
        DataSet thisDataSet = new DataSet();
        SqlDataAdapter custAdapter = new SqlDataAdapter(
             "SELECT * FROM Customers", thisConnection);
        SqlDataAdapter orderAdapter = new SqlDataAdapter(
             "SELECT * FROM Orders", thisConnection);
        custAdapter.Fill(thisDataSet, "Customers");
        orderAdapter.Fill(thisDataSet, "Orders");
        DataRelation custOrderRel = thisDataSet.Relations.Add("CustOrders",
             thisDataSet.Tables["Customers"].Columns["CustomerID"],
             thisDataSet.Tables["Orders"].Columns["CustomerID"]);
        foreach (DataRow custRow in thisDataSet.Tables["Customers"].Rows) {
            Console.WriteLine("Customer ID: " + custRow["CustomerID"] +
                              " Name: " + custRow["CompanyName"]);
            foreach (DataRow orderRow in custRow.GetChildRows(custOrderRel)) {
                Console.WriteLine("  Order ID: " + orderRow["OrderID"]);
            }
        }
        thisConnection.Close();
    }
}