public void Linq43()
{
List customers = GetCustomerList();
var customerOrderGroups =
from c in customers
select
new
{
c.CompanyName,
YearGroups =
from o in c.Orders
group o by o.OrderDate.Year into yg
select
new
{
Year = yg.Key,
MonthGroups =
from o in yg
group o by o.OrderDate.Month into mg
select new { Month = mg.Key, Orders = mg }
}
};
ObjectDumper.Write(customerOrderGroups, 3);
}
Result
CompanyName=Alfreds Futterkiste YearGroups=...
YearGroups: Year=1997 MonthGroups=...
MonthGroups: Month=8 Orders=...
Orders: OrderID=10643 OrderDate=8/25/1997 Total=814.50
MonthGroups: Month=10 Orders=...
Orders: OrderID=10692 OrderDate=10/3/1997 Total=878.00
Orders: OrderID=10702 OrderDate=10/13/1997 Total=330.00
YearGroups: Year=1998 MonthGroups=...
MonthGroups: Month=1 Orders=...
Orders: OrderID=10835 OrderDate=1/15/1998 Total=845.80
MonthGroups: Month=3 Orders=...
Orders: OrderID=10952 OrderDate=3/16/1998 Total=471.20
MonthGroups: Month=4 Orders=...