public static List <string> FindOrderByRegion(string region, DateTime startDate, DateTime endDate) { NORTHWNDEntities db = new NORTHWNDEntities(); List <string> result = new List <string>(); using (db) { // Thx to vic.alexiev form here http://forums.academy.telerik.com/107782/databases-%D0%B4%D0%BE%D0%BC%D0%B0%D1%88%D0%BD%D0%BE-entity-framework-2-5-%D0%B7%D0%B0%D0%B4%D0%B0%D1%87%D0%B8 var salesResult = from salesByYear in db.Sales_by_Year(startDate, endDate) join orders in db.Orders.Where(o => o.ShipRegion == region) on salesByYear.OrderID equals orders.OrderID select salesByYear; foreach (var sale in salesResult) { result.Add(String.Format("{0} | {1} | {2} | {3}", sale.OrderID, sale.ShippedDate, sale.Subtotal, sale.Year)); } } Console.WriteLine(); return(result); }