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 > 0)
            {
                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 > 0)
            {
                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)
        {

        }
    }
}