注意：对联接运算的结果进行排序。 请注意，排序在联接之后执行。 虽然可以在联接之前将 orderby 子句用于一个或多个源序列，不过通常不建议这样做。 某些 LINQ 提供程序可能不会在联接之后保留该排序。
在查询表达式中，orderby 子句可导致返回的序列或子序列（组）以升序或降序排序。 若要执行一个或多个次级排序操作，可以指定多个键。 元素类型的默认比较器执行排序。 默认排序顺序为升序。
以下示例对学生的姓氏进行主要排序，然后对其名字进行次要排序。
class OrderbySample2
{
// The element type of the data source.
public class Student
{
public string First { get; set; }
public string Last { get; set; }
public int ID { get; set; }
} public static List<Student> GetStudents()
{
// Use a collection initializer to create the data source. Note that each element
// in the list contains an inner sequence of scores.
List<Student> students = new List<Student>
{
new Student {First="Svetlana", Last="Omelchenko", ID=},
new Student {First="Claire", Last="O'Donnell", ID=},
new Student {First="Sven", Last="Mortensen", ID=},
new Student {First="Cesar", Last="Garcia", ID=},
new Student {First="Debra", Last="Garcia", ID=}
}; return students; }
static void Main(string[] args)
{
// Create the data source.
List<Student> students = GetStudents(); // Create the query.
IEnumerable<Student> sortedStudents =
from student in students
orderby student.Last ascending, student.First ascending
select student; // Execute the query.
Console.WriteLine("sortedStudents:");
foreach (Student student in sortedStudents)
Console.WriteLine(student.Last + " " + student.First); // Now create groups and sort the groups. The query first sorts the names
// of all students so that they will be in alphabetical order after they are
// grouped. The second orderby sorts the group keys in alpha order.
var sortedGroups =
from student in students
orderby student.Last, student.First
group student by student.Last[] into newGroup
orderby newGroup.Key
select newGroup; // Execute the query.
Console.WriteLine(Environment.NewLine + "sortedGroups:");
foreach (var studentGroup in sortedGroups)
{
Console.WriteLine(studentGroup.Key);
foreach (var student in studentGroup)
{
Console.WriteLine(" {0}, {1}", student.Last, student.First);
}
} // Keep the console window open in debug mode
Console.WriteLine("Press any key to exit.");
Console.ReadKey();
}
}
/* Output:
sortedStudents:
Garcia Cesar
Garcia Debra
Mortensen Sven
O'Donnell Claire
Omelchenko Svetlana sortedGroups:
G
Garcia, Cesar
Garcia, Debra
M
Mortensen, Sven
O
O'Donnell, Claire
Omelchenko, Svetlana
*/