C#菜鸟求助，winForm 问题
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;
using System.Data.SqlClient;

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

        SqlConnection conn;
        private void Form1_Load(object sender, EventArgs e)
        {
            conn = new SqlConnection("server=.;database=StuffDB;integrated security=SSPI");
            Load();
        }
        public DataSet getds(String sql)
        {
            try
            {
                SqlCommand cmd = new SqlCommand(sql, conn);
                SqlDataAdapter sda = new SqlDataAdapter();
                sda.SelectCommand = cmd;
                DataSet ds = new DataSet();
                sda.Fill(ds);
                cmd.Dispose();
                return ds;
            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.Message);
                return null;
            }

        }
        public void ExecuteSql(String sql)
        {
            conn.Open();
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            cmd.CommandText = sql;
         &n