static void Main(string[] args)
        {
            IList<Order> orderList = new List<Order>() {
  new Order() { Id = 1, OrderDateTime = new DateTime(2019, 11, 12, 22, 45, 12, 004), CustomerName = "ABC", Status = "Completed",DoneBy="Cenk"} ,
  new Order() { Id = 2, OrderDateTime = new DateTime(2019, 11, 12, 22, 45, 12, 004),  CustomerName = "A", Status = "Ccancelled",DoneBy="Cenk" } ,
  new Order() { Id = 3, OrderDateTime = new DateTime(2022, 07, 12, 22, 45, 12, 004),  CustomerName = "dsds", Status = "Contiues",DoneBy="Cenk" } ,
  new Order() { Id = 4, OrderDateTime = new DateTime(2022, 08, 12, 22, 45, 12, 004) , CustomerName = "dsds", Status = "Completed",DoneBy="Cenk"} ,
  new Order() { Id = 5, OrderDateTime = new DateTime(2022, 09, 12, 22, 45, 12, 004) , CustomerName = "jdsj",Status = "Completed",DoneBy="Cenk" }
  };

            // OrderDetail collection
            IList<OrderDetail> orderDetailList = new List<OrderDetail>() {
  new OrderDetail() { Id = 1, ProductCode = "12345", ProductName = "modem1",BuyQuantity=1,SellQuantity=10,CostRatio=2 , UnitCost=5,TotalBuyPrice=10,TotalSellPrice=15,Status = "Completed",ShippingNumber="Cenk", TrackingNumber="72827", Description="Test", OrderId=1, VendorId=2} ,
  new OrderDetail() { Id = 2, ProductCode = "Erf7899", ProductName = "modem2",BuyQuantity=2,SellQuantity=10,CostRatio=2 , UnitCost=5,TotalBuyPrice=10,TotalSellPrice=15,Status = "Contiunes",ShippingNumber="Cenk", TrackingNumber="72827", Description="Test", OrderId=2, VendorId=1 } ,
  new OrderDetail() { Id = 3, ProductCode = "0090owd", ProductName = "modem3",BuyQuantity=10,SellQuantity=15,CostRatio=2 , UnitCost=1,TotalBuyPrice=10,TotalSellPrice=15,Status = "Completed",ShippingNumber="Cenk", TrackingNumber="72827", Description="Test", OrderId=2, VendorId=2 } ,
  new OrderDetail() { Id = 4, ProductCode = "fse929", ProductName = "modem4",BuyQuantity=11,SellQuantity=15,CostRatio=2 , UnitCost=5,TotalBuyPrice=10,TotalSellPrice=15,Status = "Cancelled",ShippingNumber="Cenk", TrackingNumber="72827", Description="Test", OrderId=2, VendorId=1} ,
  new OrderDetail() { Id = 5, ProductCode = "1009ksks", ProductName = "modem5",BuyQuantity=19,SellQuantity=1,CostRatio=2 , UnitCost=1,TotalBuyPrice=10,TotalSellPrice=15,Status = "Completed",ShippingNumber="Cenk", TrackingNumber="72827", Description="Test", OrderId=3, VendorId=2 },
      new OrderDetail() { Id = 6, ProductCode = "556dhdk", ProductName = "modem6",BuyQuantity=9,SellQuantity=13,CostRatio=2 , UnitCost=5,TotalBuyPrice=10,TotalSellPrice=15,Status = "Completed",ShippingNumber="Cenk", TrackingNumber="72827", Description="Test", OrderId=1, VendorId=2 } ,
      new OrderDetail() { Id = 7, ProductCode = "99999", ProductName = "modem7",BuyQuantity=10,SellQuantity=14,CostRatio=2 , UnitCost=15,TotalBuyPrice=10,TotalSellPrice=15,Status = "Completed",ShippingNumber="Cenk", TrackingNumber="72827", Description="Test", OrderId=3, VendorId=1 },
      new OrderDetail() { Id = 8, ProductCode = "00000", ProductName = "modem8",BuyQuantity=1,SellQuantity=15,CostRatio=2 , UnitCost=1,TotalBuyPrice=10,TotalSellPrice=15,Status = "Completed",ShippingNumber="Cenk", TrackingNumber="72827", Description="Test", OrderId=4, VendorId=1 }
  };

            // vendor collection
            IList<Vendor> vendorList = new List<Vendor>() {
  new Vendor() { Id = 1, Name = "Vendor1", Address = "ABC Address", Email = "Email", PhoneNumber="1234353", MainResponsibleName="test", AssistantResponsibleName="test1"} ,
  new Vendor() { Id = 2, Name = "Vendor1", Address = "ABC Address", Email = "Email", PhoneNumber="1234353", MainResponsibleName="test", AssistantResponsibleName="test1" }

  };

            // LINQ Query Syntax to find out teenager students

            var result1 = from order in orderList
                         from orderdetail in orderDetailList
                         where order.Id == orderdetail.OrderId && order.OrderDateTime > DateTime.Now.AddMonths(-4)
                         select new
                         {
                             order.OrderDateTime,
                             orderdetail.TotalSellPrice
                         };
            var result2 = from order in result1
                          group order by new
                          {
                              order.OrderDateTime.Year,
                              order.OrderDateTime.Month
                          }
                         into grup
                          select new
                          {
                              year = grup.Key.Year,
                              month = grup.Key.Month,
                              total = grup.Sum(m => m.TotalSellPrice)
                          };




        }