var queryOldOrders =
from o in ds.Orders
where o.OrderDate.Year <= 1996
select o;

var queryLowFreightOrders =
from o in ds.Orders
where o.Freight < 50
select o;

DataTable oldOrders = queryOldOrders.CopyToDataTable();
DataTable lowFreightOrders = queryLowFreightOrders.CopyToDataTable();

// nalezen prniku dvou dotaz
var queryOrders= oldOrders.AsEnumerable().Intersect(
lowFreightOrders.AsEnumerable(),
DataRowComparer.Default);

DataTable orders = queryOrders.CopyToDataTable();
