Linq to sql 增删改查（转帖）

http://blog.csdn.net/pan_junbiao/article/details/7015633 （LINQ To SQL 语法及实例大全）

代码

Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/-->using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data.Common;

using System.Collections.Generic;

namespace FirstLinq

{

public partial class _Default : System.Web.UI.Page

{

NorthwindDataContext ctx = new NorthwindDataContext("Data Source=ZHANGSHUQIANG;Initial Catalog=Northwind;Persist Security Info=True;User ID=sa;Password=sa");

protected void Page_Load(object sender, EventArgs e)

{

Linq1();

Linq2();

Linq3();

}

/// <summary>

/// 增删改查

/// </summary>

private void Linq3()

{

//增

t_User user = new t_User();

user.UserName = "大气象";

user.Pwd = "123456";

ctx.t_User.InsertOnSubmit(user);//以前的方法是Add();

ctx.SubmitChanges();

//改

//参考这样的语法string s = (from a in ctx.Customers select a).Single(a => a.ID == 2);

t_User userUpdate = ctx.t_User.SingleOrDefault(t_User => t_User.ID == 2);//Single与SingleOrDefault没区别

userUpdate.UserName = "大气象1";

ctx.SubmitChanges();

//删

t_User userDelete = (from userinfo in ctx.t_User where userinfo.ID == 1 select userinfo).FirstOrDefault();

if (userDelete != null)

{

ctx.t_User.DeleteOnSubmit(userDelete);

ctx.SubmitChanges();

}

}

/// <summary>

/// 熟悉Linq to sql语法

/// </summary>

private void Linq2()

{

Customers customer = new Customers();

//执行普通的sql语句，查询CustomerID="ANATR"的记录

IEnumerable<Customers> customers = ctx.ExecuteQuery<Customers>("select * from Customers where CustomerID='ANATR'");

customer = customers.First();

Response.Write(customer.CustomerID);

//使用Linq查询单条记录

var cus = from c in ctx.Customers where c.CustomerID.Equals("ANATR") select c;

customer = cus.First();

Response.Write(customer.CompanyName);

//查询结果集，语法：from 临时表名 in 表集合 orderby 临时表名.字段名 升级序 select 临时表名

gdvCustomers.DataSource = from cust in ctx.Customers where cust.CustomerID != "ANATR" orderby cust.CompanyName descending select cust;

gdvCustomers.DataBind();

}

/// <summary>

/// 熟悉一下linq语法，变量的定义类似js，无须声明类型。

/// </summary>

private void Linq1()

{

var age = 29;

var username = "greatverve";

var userlist = new[] { "a", "b", "c" };

foreach (var user in userlist)

{

Response.Write(user);

}

}

}

}

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