Linq to sql 增删改查（转帖）

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);

            }

        }

    }

}

http://www.cnblogs.com/greatverve/archive/2010/05/13/1734236.html