asp.net_linq language integration query example

Little scum · Posted on 5/7/2015 10:40:57 AM

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace Linq
{
/*
LINQ的写法：
from 临时变量 in 实现IEnumerable<T>接口的对象(集合)
where条件表达式
[orderby条件]
[group by 条件]
select 临时变量中被查询的值
*/
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
string[] arr = { "sfssdfsdfdf", "234234", "sdfssdfdfdf", "dsgsdf234dfg", "234sdf", "45gdfg34fgdfg" };
//var:匿名变量
var strArr =
//linq语句：从数组里查询所有元素放到strarr集合里
from str in arr
where str.Length > 10
orderby str descending
select str;
//IEnumerable<T>接口的对象strArr，是可以用foreach遍历的
foreach (string str in strArr)
{
//Response.Write(str+"<br>");
}
//添加5个用户对象到集合里
List<UserInfo> users = new List<UserInfo>();
UserInfo user1 = new UserInfo(1, "张三", "男", 19, "34534656");
UserInfo user2 = new UserInfo(2, "放到", "男", 22, "34534656");
UserInfo user3 = new UserInfo(3, "的", "女", 39, "34534656");
UserInfo user4 = new UserInfo(4, "更好", "女", 18, "34534656");
UserInfo user5 = new UserInfo(5, "u影", "男", 29, "34534656");
users.Add(user1);
users.Add(user2);
users.Add(user3);
users.Add(user4);
users.Add(user5);
//linq子句：
//from select where group orderby join let into
var uArr = from u in users where u.UserSex == "女" orderby u.UserAge select u;
foreach (var user in uArr)
{
//Response.Write("id:"+user.UserID+",名字："+user.UserName+",性别："+user.UserSex+",年龄："+user.UserAge+
// ",电话:"+user.UserTel+ "<br>");
}
//group by
var uArr2 = from u in users group u by u.UserSex;
for (int i = 0; i < uArr2.Count(); i++)
{
foreach (var user in uArr2.ElementAt(i))
{
//Response.Write("id:" + user.UserID + ",名字：" + user.UserName + ",性别：" + user.UserSex + ",年龄：" + user.UserAge +
// ",电话:" + user.UserTel + "<br>");
}
}
//
List<ScoreInfo> scores = new List<ScoreInfo>();
ScoreInfo s1 = new ScoreInfo(1, 1, 45);
ScoreInfo s2 = new ScoreInfo(2, 2, 92);
ScoreInfo s3 = new ScoreInfo(3, 4, 89);
ScoreInfo s4 = new ScoreInfo(4, 5, 97);
scores.Add(s1);
scores.Add(s2);
scores.Add(s3);
scores.Add(s4);
var uArr3 = from u in users
join s in scores on u.UserID equals s.UserID
select new { u.UserName,u.UserSex,u.UserAge,u.UserTel, s.Score };
foreach (var user in uArr3)
{
Response.Write("名字：" + user.UserName + ",性别：" + user.UserSex + ",年龄：" + user.UserAge +
",电话:" + user.UserTel + ",成绩："+user.Score+ "<br>");
}
//let
//var uArr4 = from s in scores where s.Score >= 90 select s.UserID into id
//into
}
}
}
}

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[ASP.NET] asp.net_linq language integration query example

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