export dataset to xml

orderProductsRel.Nested = true;

SqlDataAdapter custAdapter = new SqlDataAdapter("select * from Customers",conn);
SqlDataAdapter orderAdapter = new SqlDataAdapter("select * from orders", conn);
SqlDataAdapter detailsAdapter = new SqlDataAdapter("select * from [order details]", conn);
SqlDataAdapter productsAdapter = new SqlDataAdapter("select * from Products",conn);

custAdapter.Fill(thisDataset, "Customers");
orderAdapter.Fill(thisDataset, "orders");
detailsAdapter.Fill(thisDataset, "order details");
productsAdapter.Fill(thisDataset, "Products");
//DataColumn d = new DataColumn();
//d.ColumnName ="orderID";
//d.DataType =(System .Type .st) sqlDbType .Text ;
DataRelation custOrderRel =
thisDataset.Relations.Add("custOrders",
thisDataset.Tables["Customers"].Columns["CustomerID"],
thisDataset.Tables["orders"].Columns["CustomerID"]);
custOrderRel.Nested = true;
DataRelation orderDetailRel = thisDataset.Relations.Add("OrderDetali",
thisDataset.Tables["orders"].Columns["orderID"],
thisDataset.Tables["order details"].Columns["orderID"]);
orderDetailRel.Nested = true;
DataRelation orderProductsRel= thisDataset.Relations.Add("OrderProducts",
                   thisDataset.Tables["Products"].Columns["ProductID"],
                   thisDataset.Tables["order details"].Columns["ProductID"]);
orderProductsRel.Nested = true;
thisDataset.WriteXmlSchema("c:\\wsc.xml");
thisDataset.WriteXml("c:\\s.xml");