linq 学习日记-where

引用地址：http://www.cnblogs.com/young18/archive/2007/06/05/772127.html

using#region using
using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Text;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Collections.Generic;
using System.Collections;
#endregion

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        根据条件查询数组#region 根据条件查询数组
        Response.Write("<hr>列出数组中字符长度大于等于6的字符串数组：<br>");
        string[] Demo1 = { "Ajax", "Csharp", "Javascript", "Css Desige", "Asp.net", "Gis" };
        var books = from n in Demo1 
                    where n.Length >= 6 
                    select n;

        foreach (var book in books){
            Response.Write(string.Format("<span class='result'>{0}</span>", book));
        }
        #endregion

        where查询的Lambda表达式#region where查询的Lambda表达式
        Response.Write("<hr>where查询的快捷方法：<br>");
        var books2 = Demo1.Where(book => book.Length >= 6);

        foreach (var book in books2)
        {
            Response.Write(string.Format("<span class='result'>{0}</span>", book));
        }
        #endregion
        
        根据条件查询集合体#region 根据条件查询集合体

        Response.Write("<hr>列出集合中语言为Chinese的学生：<br>");
        List<Student> Demo2 = GetStudents();
        var students1 = from n in Demo2
                        where n.Language == "Chinese"
                        select n.Name;

        foreach (var student in students1){
            Response.Write(string.Format("<span class='result'>{0}</span>", student));
        }
        #endregion

        根据条件查询集合体#region 根据条件查询集合体
        Response.Write("<hr>列出集合中年龄大于等于20的英国或苏格兰学生：<br>");
        var students2 = from n in Demo2
                        where (n.Language == "English" || n.Language == "Scotland") && n.Age >= 20
                        select n;

        foreach (var student in students2){
            Response.Write(string.Format("<span class='result'>{0}</span>", student.Name));
        }
        #endregion
    }

    构造一个学生集合体#region 构造一个学生集合体
    private List<Student> GetStudents()
    {
        List<Student> students = new List<Student> { 
             new Student{ Name="YOUNG", Age=25, Language="Chinese"},
             new Student{ Name="JESSIE", Age=21, Language="Scotland"},
             new Student{ Name="KELLY", Age=18, Language="English"},
             new Student{ Name="JUNE", Age=20, Language="English"},
             new Student{ Name="ADRIAN", Age=22, Language="Italy"},
             new Student{ Name="BRUCE", Age=17, Language="Scotland"},
             new Student{ Name="BRANT", Age=30, Language="Germany"},
             new Student{ Name="BEN", Age=25, Language="Chinese"}
        };
        return students;
    }
    #endregion
}

学生类#region 学生类
class Student
{
    public int Age { get; set; }
    public string Name { get; set; }
    public string Language { get; set; }
}
#endregion

显示结果：