Question for DataTables Replation in a DataSet?

Can anyone explain what the relations in DataSet do and what it for? I have run the code below with and without the relation snippet, and I see not different. Can you tell me what the relation in a DataSet doing?

protectedvoid Page_Load(object sender,EventArgs e)

{

//1. Db Connection

SqlConnection myConn =newSqlConnection(myConnString);

myConn.Open();

//2. DataSet

DataSet ds =newDataSet();

//3. Adapter command and fillin dataSet

//--1). Customer SQL Adapter--

string sSQL ="Select CustomerID, Phone From Customers Where CustomerID ='VINET'";

SqlDataAdapter myCommand;

myCommand =newSqlDataAdapter(sSQL, myConn);

myCommand.Fill(ds,"Customers");

//--2) Orders SQL Adapter--

sSQL ="Select o.OrderID, o.CustomerID, o.OrderDate, o.RequiredDate, o.Freight, o.ShippedDate From Customers c, Orders o Where c.CustomerID = o.CustomerID AND o.CustomerID ='VINET' ";

myCommand =newSqlDataAdapter(sSQL, myConn);

myCommand.Fill(ds,"Orders");

myConn.Close();

//4. Relation snippet

DataColumn dc1 = ds.Tables["Customers"].Columns["CustomerID"];

DataColumn dc2 = ds.Tables["Orders"].Columns["CustomerID"];

DataRelation dRel = new DataRelation("CustomerOrder", dc1, dc2);

ds.Relations.Add(dRel); //add relation to DataSet and bind data

GridView1.DataSource = ds.Tables["Customers"].DefaultView;

GridView1.DataBind();

GridView2.DataSource = ds.Tables["Orders"].DefaultView;

GridView2.DataBind();

}

[3725 byte] By [ColinTo] at [2007-12-22]