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

using System.IO;
using System.Data.OleDb;

//access db1.mdb
//table mytable
//a text
//b text


namespace WindowsFormsApplication4
{
    public partial class Form1 : Form
    {

        //定義OLE======================================================
        //1.檔案位置
        private const string FileName = "db1.mdb";
        //2.提供者名稱
        private const string ProviderName = "Microsoft.Jet.OLEDB.4.0;";
        //3.帳號
        private const string UserId = ";";
        //4.密碼
        private const string Password = ";";
        //=============================================================

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string DataSource = Directory.GetCurrentDirectory() + "\\" + FileName;
            if (!File.Exists(DataSource))
            {
                MessageBox.Show("檔案不存在");
                return;
            }
            //連線字串
            string cs =
                    "Data Source=" + DataSource + ";" +
                    "Provider=" + ProviderName +
                    "User Id=" + UserId +
                    "Password=" + Password;


            using (OleDbConnection cn = new OleDbConnection(cs))
            {
                string qs = "SELECT b FROM mytable where a  = '" + textBox1.Text.ToString() + "';";
                if (cn.State == ConnectionState.Closed)
                {
                    cn.Open();
                    using (OleDbCommand cmd = new OleDbCommand(qs, cn))
                    {
                        using (OleDbDataReader dr = cmd.ExecuteReader())
                        {
                            dr.Read();
                            textBox2.Text = dr["b"].ToString();
                        }
                    }
                }


            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            label1.Text = "欄位 A";
            label2.Text = "欄位 B";
            textBox1.Text = "a01";
            textBox2.Text = "欄位 B 的值 會出現在這裡";

        }
    }
}