简单的linq to sql

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首先，是使用实体层映射的方式去访问。1.实体层定义

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Data.Linq.Mapping;namespace LinqtoSql{    [Table(Name = "UserInfo")]//要映射的数据库表名称    [Database]    class Entity    {        [Column(Name = "UserID")]//表字段        public string UserID { get; set; }        [Column(Name = "UserPassword")]        public string UserPassword { get; set; }        [Column(Name = "ChatName")]        public string ChatName { get; set; }        [Column(Name = "IP")]        public string IP { get; set; }        [Column(Name = "port")]        public int Port { get; set; }    }}

下面则是使用linq去通过实体层去使用数据库中的数据

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;using System.Data.Linq;using System.Data.SqlClient;namespace LinqtoSql{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        private void Form1_Load(object sender, EventArgs e)        {            Entity en= linq();            textBox1.Text = en.ChatName;        }        private Entity linq()        {            SqlConnection conn = new SqlConnection();            conn.ConnectionString = "Data Source=niit8-124;Database=chatUser;uid=sa;pwd=123456";            DataContext context = new DataContext(conn.ConnectionString);            Entity e = (from f in context.GetTable()                        where f.Port == 22                        select f).First();            return e;        }    }}

还有就是不实用实体层去使用数据库的内容

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Xml;using System.Data;using System.Data.SqlClient;namespace ConsoleApplication21{    class Program    {        static void Main(string[] args)        {            DataTable dt=test();            IEnumerable rows = dt.AsEnumerable();            var result = rows.Where(u => u["stuName"].ToString().Trim() == "张龙").ToList();            Console.WriteLine(result[0].ItemArray[0].ToString());              }        public static DataTable test()        {            string s = "Data Source=niit8-124;Database=studentinfo;uid=sa;pwd=123456";            SqlConnection conn = new SqlConnection(s);            SqlDataAdapter da = new SqlDataAdapter("select * from student", conn);            DataSet ds = new DataSet();            da.Fill(ds);            DataTable dt = ds.Tables[0];            return dt;        }}    }