1、什么是ADO.NET?     (是一种数据库访问技术)

      ADO.NET的名称起源于ADO（ActiveX Data Objects），是一个COM组件库，用于在以往的Microsoft技术中访问数据。之所以使用ADO.NET名称，是因为Microsoft希望表明，这是在NET编程环境中优先使用的数据访问接口。

2、ADO.NET 的作用？

通过程序来操作数据库

3、连接，基础增删改：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Data.SqlClient;namespace ConsoleApplication1{    class Program    {        static void Main(string[] args)        {            //连接字符串            string sql = "server=.;database=Data0216;user=sa;pwd=123;";            //数据库连接类            SqlConnection conn = new SqlConnection(sql);            //数据库操作类            SqlCommand cmd = conn.CreateCommand();            //cmd.CommandText = "insert into Users values('zhaoliu','1234','赵六',1,'2004-4-4','N001');";            //cmd.CommandText = "update Users set NickName = '小六子' where username = 'zhaoliu'";            //编写TSQL语句            cmd.CommandText = "delete from Users where username='zhaoliu'";            //打开数据库连接            conn.Open();            //执行操作            cmd.ExecuteNonQuery();            //关闭数据库连接            conn.Close();            Console.ReadLine();        }    }}

4、查询：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Data.SqlClient;namespace ConsoleApplication2{    class Program    {        static void Main(string[] args)        {            string sql = "server=.;database=Data0216;user=sa;pwd=123";            SqlConnection conn = new SqlConnection(sql);            SqlCommand cmd = conn.CreateCommand();            cmd.CommandText = "select *from Users";            conn.Open();            SqlDataReader dr = cmd.ExecuteReader();            if (dr.HasRows)            {                while (dr.Read())                {                    string ids = dr[0].ToString();                    string username = dr[1].ToString();                    string birthday = dr["Birthday"].ToString();                    string password = dr["PassWord"].ToString();                    string nickname = dr["NickName"].ToString();                    string sex = dr["Sex"].ToString();                    string nation = dr["Nation"].ToString();                    Console.WriteLine(ids + " | " + username + " | " + password + " | " + nickname + " | " + sex + " | " + birthday + " | " + nation);                }            }            conn.Close();            Console.ReadKey();        }    }}

5、完整的增删改:

删除：

using System;using System.Collections.Generic;using System.Data.SqlClient;using System.Linq;using System.Text;namespace ConsoleApplication1{    class Program    {        static void Main(string[] args)        {            string sql = "server=.;database=Data0216;user=sa;pwd=123";            SqlConnection conn = new SqlConnection(sql);            SqlCommand cmd = conn.CreateCommand();            cmd.CommandText = "delete from users where username='zhangsan'";            conn.Open();            int a = cmd.ExecuteNonQuery();            if (a > 0) Console.WriteLine("删除成功，本次共删除" + a + "行");            else Console.WriteLine("删除失败，本次未删除任何数据");            conn.Close();            Console.ReadLine();        }    }}

增和改：

using System;using System.Collections.Generic;using System.Data.SqlClient;using System.Linq;using System.Text;namespace ConsoleApplication3{    class Program    {        static void Main(string[] args)        {            bool has = false;            string sql = "server=.;database=Data0216;user=sa;pwd=123";            SqlConnection conn = new SqlConnection(sql);            SqlCommand cmd = conn.CreateCommand();            Console.Write("请输入要修改的用户的用户名：");            string name = Console.ReadLine();            cmd.CommandText = "select *from Users where UserName = '" + name + "'";            conn.Open();            SqlDataReader dr = cmd.ExecuteReader();            if (dr.HasRows)            {                has = true;            }            conn.Close();            if (!has)                Console.WriteLine("用户名输入错误！查无此用户");            else            {                Console.WriteLine("已查询到此用户，请输入更改的信息");                Console.Write("请输入修改后的密码：");                string password = Console.ReadLine();                Console.Write("请输入修改后的昵称：");                string nickname = Console.ReadLine();                Console.Write("请输入修改后的性别：");                string sex = Console.ReadLine();                Console.Write("请输入修改后的生日：");                string birthday = Console.ReadLine();                Console.Write("请输入修改后的民族：");                string nation = Console.ReadLine();                cmd.CommandText = "update Users set PassWord='" + password + "',NickName='" + nickname + "',Sex='" + sex + "',Birthday='" + birthday + "',Nation='" + nation + "' where UserName = '" + name + "'";                conn.Open();                int aaa = cmd.ExecuteNonQuery();                conn.Close();                if (aaa > 0) Console.WriteLine("修改成功");                else Console.WriteLine("修改失败");            }            Console.ReadLine();        }    }}