c#程序问题各位大哥帮帮看下 --我 才学习的 看吧 懂~~~~

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

namespace WindowsFormsApplication3
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private DataSet ds = new DataSet();
private System.Data.SqlClient.SqlConnection conn = null;
private System.Data.SqlClient.SqlDataAdapter da = null;
private const string DRIVER = "server=.;database=northwind;uid=sa;pwd=sa";
private const string sql_select = "select * from region";

private void Form1_Load(object sender, EventArgs e)
{
conn = new SqlConnection(DRIVER);
da = new SqlDataAdapter(sql_select,conn);