LINQ查询，当一列为distinct时，返回按多列分组的整个对象

// 假设有一个包含对象的集合
List<Person> persons = new List<Person>
{
    new Person { Name = "Alice", Age = 25, City = "New York" },
    new Person { Name = "Bob", Age = 30, City = "London" },
    new Person { Name = "Alice", Age = 28, City = "Paris" },
    new Person { Name = "Bob", Age = 35, City = "New York" },
    new Person { Name = "Alice", Age = 25, City = "London" }
};

// 使用LINQ查询按姓名和年龄分组对象
var groupedPersons = persons.GroupBy(p => new { p.Name, p.Age });

// 遍历分组结果并输出
foreach (var group in groupedPersons)
{
    Console.WriteLine($"Group: Name={group.Key.Name}, Age={group.Key.Age}");
    foreach (var person in group)
    {
        Console.WriteLine($"Person: Name={person.Name}, Age={person.Age}, City={person.City}");
    }
    Console.WriteLine();
}