在点表达式中使用与查询表达式中相同的匿名类型:
var qry = cust.GroupBy(cm => new { cm.Customer, cm.OrderDate },
(key, group) => new { Key1 = key.Customer, Key2 = key.OrderDate,
Count = group.Count() });
(在真正的IDE中,我将(key, group)
在该cm
参数下排队,但随后它将包裹在SO中。)