C#3.0新特性示例学习（七）－Linq to object(4)分组查询

 1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5
6 namespace TestLinQ2
7 {
8 public class Book
9 {
10 public string Title { set ; get ; }
11 public Author Book_Author { set ; get ;}
12 public float Price { set ; get ; }
13 }
14 public class Author
15 {
16 public string Name { set ; get ; }
17 public string Address { set ; get ;}
18 }
19
20 public class TestLinq3
21 {
22 public void TestMethod()
23 {
24 List < Book > bookList = new List < Book >
25 {
26 new Book[color=]... {Title = " C#高级编程 " ,Book_Author = new Author {Name = " 黄老邪 " ,Address = " 桃花岛 " } ,Price = 128f} ,
27 new Book[color=]... {Title = " Think in Java " ,Book_Author = new Author {Name = " 欧阳峰 " ,Address = " 白驼山 " } ,Price = 128f} ,
28 new Book[color=]... {Title = " silverlight " ,Book_Author = new Author {Name = " 一灯大师 " ,Address = " 大理 " } ,Price = 128f} ,
29 new Book[color=]... {Title = " JavaFx " ,Book_Author = new Author {Name = " 洪七公 " ,Address = " 临安 " } ,Price = 125f}
30
31 } ;
32
33
34 /// 查询所有黄老邪写的书
35 // var mybook = bookList
36 // .Where(book => book.Book_Author.Name.Equals("黄老邪"))
37 /// 注意下面这种写法，象不象是匿名类
38 // .Select(book => new { Title=book.Title,MyAuthor=book.Book_Author.Name,My_Price=book.Price });
39
40 // foreach (var item in mybook)
41 // {
42 // Console.Write(string.Format("书名{0} 价格{1} 作者{2}",item.Title , item.My_Price.ToString() , item.MyAuthor));
43
44 // }
45
46
47 /// 分组查询 按价格分组
48 var mybook = bookList
49 .GroupBy(book => book.Price);
50
51
52
53 foreach (var item in mybook)
54 {
55 /// 显示每组的数据，聚合数据
56 Console.WriteLine( string .Format( " 分组依据：{0} 每组最大的书名{1} 每组数量{2} " , item.Key,item.Max(book => book.Title),item.Count()));
57
58 foreach (var newbook in item)
59 {
60 /// 这个可以遍历每个组里的数据了
61 Console.WriteLine(newbook.Title);
62 }
63 }
64
65 }
66 }
67 }