2017-4-18 ADO.NET

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[].ToString();
                    string username = dr[].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 > ) 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 > ) Console.WriteLine("修改成功");
                else Console.WriteLine("修改失败");
            }

            Console.ReadLine();

        }
    }
}