一、数据准备
public class Student
{
public int ID { get; set; }
public string Name { get; set; }
public string Gender { get; set; }
public string Branch { get; set; }
public int Age { get; set; }
public static List<Student> GetAllStudents()
{
return new List<Student>()
{
new Student { ID = 1001, Name = "玲玲", Gender = "Female",
Branch = "CSE", Age = 20 },
new Student { ID = 1002, Name = "张三", Gender = "Male",
Branch = "ETC", Age = 21 },
new Student { ID = 1003, Name = "李四", Gender = "Male",
Branch = "CSE", Age = 21 },
new Student { ID = 1004, Name = "王五", Gender = "Male",
Branch = "CSE", Age = 20 },
new Student { ID = 1005, Name = "珊珊", Gender = "Female",
Branch = "ETC", Age = 20 },
new Student { ID = 1006, Name = "涵涵", Gender = "Female",
Branch = "CSE", Age = 21 },
new Student { ID = 1007, Name = "钱六", Gender = "Male",
Branch = "CSE", Age = 22 },
new Student { ID = 1008, Name = "婷婷", Gender = "Female",
Branch = "CSE", Age = 20 },
new Student { ID = 1009, Name = "兰兰", Gender = "Female",
Branch = "ETC", Age = 22 },
new Student { ID = 1010, Name = "黄九", Gender = "Male",
Branch = "ETC", Age = 21 }
};
}
}
二、GroupByMultipleKeys
//Using Query Syntax
Console.WriteLine("方式一：");
var GroupByMultipleKeysQS = from std in Student.GetAllStudents()
group std by new
{
std.Branch,
std.Gender
} into stdGroup
orderby stdGroup.Key.Branch descending,
stdGroup.Key.Gender ascending
select new
{
Branch = stdGroup.Key.Branch,
Gender = stdGroup.Key.Gender,
Students = stdGroup.OrderBy(x => x.Name)
};
foreach (var group in GroupByMultipleKeysQS)
{
Console.WriteLine($"Branch:{group.Branch} Gender:{group.Gender} No of Students={group.Students.Count()}");
foreach (var student in group.Students)
{
Console.WriteLine($"ID:{student.ID},Name:{student.Name},Age:{student.Age}");
}
}
//Using Query Syntax
Console.WriteLine("方式二：");
var GroupByMultipleKeysMS = Student.GetAllStudents()
.GroupBy(x => new { x.Branch, x.Gender })
.OrderByDescending(g => g.Key.Branch).ThenBy(g => g.Key.Gender)
.Select(g => new
{
Branch = g.Key.Branch,
Gender = g.Key.Gender,
Students = g.OrderBy(x => x.Name)
});
foreach (var group in GroupByMultipleKeysMS)
{
Console.WriteLine($"Branch:{group.Branch} Gender:{group.Gender} No of Students={group.Students.Count()}");
foreach (var student in group.Students)
{
Console.WriteLine($"ID:{student.ID},Name:{student.Name},Age:{student.Age}");
}
}
三、测试结果
四、参考网址
https://dotnettutorials.net/lesson/groupby-multiple-keys-in-linq/
个人代码见....CSharpBasic\LINQTutorial.. 标签：GroupByMultipleKeys,Name,Gender,Age,LINQ,Branch,new,ID From： https://www.cnblogs.com/keeplearningandsharing/p/16628265.html