winform —— 连接数据库SQL Server 2008

using System.Data.SqlClient;命名空间
sqlconnection:数据连接类
sqlcommand:数据库操作类
sqldatareader:读取

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Data.SqlClient;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Windows.Forms;

 namespace WindowsFormsApplication7
 {
     public partial class Form1 : Form
     {
         public Form1()
         {
             InitializeComponent();
         }

         private void button1_Click(object sender, EventArgs e)
         {
             string username = textBox1.Text;
             string upass = textBox2.Text;

             //第一步：连接到数据库
             SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=");
             conn.Open();
             //第二步：写执行语句
             SqlCommand cmd = conn.CreateCommand();//通过conn创建sqlcommand对象
             cmd.CommandText = "select *from users where uname='"+username+"' and upass='"+upass+"'";
             SqlDataReader dr = cmd.ExecuteReader();//执行查询，返回sqldatareader对象
             if (dr.Read())
             {
                 MessageBox.Show("登陆成功！");
             }
             else
             {
                 MessageBox.Show("登陆失败！");
             }

             conn.Close();
         }

         private void button2_Click(object sender, EventArgs e)
         {
             //添加数据到数据库
             string username = textBox1.Text;
             string upass = textBox2.Text;

             //第一步：连接到数据库
             SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=");
             conn.Open();
             SqlCommand cmd = conn.CreateCommand();
             cmd.CommandText = "insert into users values('"+username+"','"+upass+"')";
             int count=　cmd.ExecuteNonQuery();//增删改
             if (count > )
             {
                 MessageBox.Show("添加成功！");
             }
             else
             {
                 MessageBox.Show("添加失败！");
             }
             conn.Close();
         }

         private void button3_Click(object sender, EventArgs e)
         {
             string code = textBox3.Text;
             string uname = textBox1.Text;
             string upass = textBox2.Text;
             //第一步：连接到数据库
             SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=");
             conn.Open();
             SqlCommand cmd = conn.CreateCommand();
             cmd.CommandText = "update users set uname='"+uname+"',upass='"+upass+"' where code="+code;
             int count=cmd.ExecuteNonQuery();
             if (count > )
             {
                 MessageBox.Show("修改成功！");
             }
             else
             {
                 MessageBox.Show("修改失败！");
             }
             conn.Close();
         }

         private void button4_Click(object sender, EventArgs e)
         {
             string code = textBox3.Text;
             SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=");
             conn.Open();
             SqlCommand cmd = conn.CreateCommand();
             cmd.CommandText = "delete from users where code="+code;
             cmd.ExecuteNonQuery();
             conn.Close();
         }

         private void Form1_Load(object sender, EventArgs e)
         {

         }
     }
 }