1.代码

//group join
            var groupJoinQS = from addr in Address.GetAddress()
                              join emp in Employee.GetAllEmployees() on addr.ID equals emp.AddressId into ADDEmp
                              select new { addr, ADDEmp };
            foreach (var item in groupJoinQS)
            {
                Console.WriteLine(item.addr);
                Console.WriteLine(item.ADDEmp);
                Console.WriteLine(item.addr.AddressLine);
                foreach (var employee in item.ADDEmp)
                {
                    Console.WriteLine("  EmployeeID : " + employee.ID + " , Name : " + employee.Name);
                }
            }

2.测试结果如下

 所以ADDEmp指的是Employee?

参考：

https://dotnettutorials.net/lesson/linq-group-join/