linqgroupbymultiplekeys.cs

var query = from order in context.Orders
            group order by new { order.Customer , order.OrderDate } into ordersForCustomer
            select
            new 
            { 
              Key1 = ordersForCustomer.Key.Customer,
              Key2=ordersForCustomer.Key.OrderDate,
              Count=ordersForCustomer.Count() 
            };