C#连接access及相关操作

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

namespace WindowsApplication1
...{
    public partial class Form1 : Form
    ...{
        public Form1()
        ...{
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        ...{
            //Login WinForm no change size
            this.FormBorderStyle =System.Windows.Forms.FormBorderStyle.FixedSingle;
            /**//*
            //Method : C# Connect Access DataBase;
            System.Data.OleDb.OleDbConnection dbconn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data source=D: est.mdb");
            //dbconn.Open();
            System.Data.OleDb.OleDbCommand myCmd = new OleDbCommand("select * from login", dbconn);
            System.Data.OleDb.OleDbDataAdapter myAdapter = new OleDbDataAdapter(myCmd);
            System.Data.DataSet myDataSet = new DataSet();
            //myAd.Fill (myDs,"login");
            try
            {
                dbconn.Open();
                myAdapter.Fill(myDataSet,"login");
            }
            catch(OleDbException)
            {
                //错误处理
            }
            finally
            {
                if (dbconn.State == ConnectionState.Open)
                    dbconn.Close();
            }
            */

            // ComboBox与数据库的绑定
            // 1、创建数据库连接
            OleDbConnection dbconn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data source=D: est.mdb");
            // 2、创建一个myDataSet
            DataSet myDataSet = new DataSet();
            dbconn.Open();
            // 3、用OleDbDataAdapter得到一个数据集
            OleDbDataAdapter myCommand = new OleDbDataAdapter("SELECT 用户名 FROM login", dbconn);
            // 4、myDataSet绑定数据表
            myCommand.Fill(myDataSet, "login");
            // 5、关闭连接
            dbconn.Close();
            // 6、榜定ComboBox组件
            this.comboBox1.DataSource = myDataSet;
            this.comboBox1.DisplayMember ="login.用户名";
            this.comboBox1.ValueMember ="login.用户名";   
        }

        
        private void button1_Click(object sender, EventArgs e)
        ...{
            if (textBox1.Text == "" || textBox2.Text =="")
            ...{
                MessageBox.Show("Please input UserName or PassWord !", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Information);
                return;
            }

            OleDbConnection dbconn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data source=D: est.mdb");
            OleDbCommand myCmd = new OleDbCommand("SELECT * FROM login WHERE 用户名='" + textBox1.Text + "'", dbconn);
            dbconn.Open();
            OleDbDataReader reader;
            reader = myCmd.ExecuteReader();

            if (reader.Read())
            ...{
                if (textBox2.Text == reader["密码"].ToString())
                ...{
                    //MessageBox.Show(textBox1.Text  + reader["密码"].ToString() + "成功登陆！",this.Text,MessageBoxButtons.OK,MessageBoxIcon.Information);
                    Form2 frm2 = new Form2();
                    frm2.Show();
                    this.Hide();
                    //dbconn.Close();
                }
            }
            else
            ...{
                MessageBox.Show("没有这个用户！",this.Text,MessageBoxButtons.OK,MessageBoxIcon.Exclamation);
                
            }

            dbconn.Close();
        }

        private void button2_Click(object sender, EventArgs e)
        ...{
            Application.Exit();
        }

        private void Form1_Closing(object sender,System.ComponentModel.CancelEventArgs e)
        ...{
            //e.Cancel = true;
        }

    }
}