C# winform 读取数据库并显示成datagrid

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.Threading.Tasks;
using System.Windows.Forms;


namespace WindowsFormsApplication2 {
    public partial class Form1 : Form {
        public Form1() {
            InitializeComponent();
        }


        private void Form1_Load(object sender, EventArgs e) {
           
        }

        private void button1_Click(object sender, EventArgs e) {
            //string sql = "select * from persons";
            //string connectstr = @"Password=myPassword;Persist Security Info=True;User ID=sa;Initial Catalog=TESTDB;Data Source=IETEST\SQLEXPRESS";
            //using (SqlConnection conn = new SqlConnection(connectstr)) {
            //    conn.Open();
            //    SqlDataAdapter ada = new SqlDataAdapter(sql, conn);
            //    DataSet ds = new DataSet();
            //    ada.Fill(ds);
            //    dataGridView1.DataSource = ds.Tables[0];
            //};

            string sql = "select * from persons";
            string conectionStr = @"Password=sa123456;Persist Security Info=True;User ID=sa;Initial Catalog=TESTDB;Data Source=IEGUORENJIE\SQLEXPRESS";
            using (SqlConnection conn = new SqlConnection(conectionStr)) {
                conn.Open();
                SqlDataAdapter ada = new SqlDataAdapter(sql, conn);
                DataSet ds = new DataSet();
                ada.Fill(ds);
                dataGridView1.DataSource = ds.Tables[0];
            }
        }

        private void toolStripMenuItem1_Click(object sender, EventArgs e) {

        }

        private void 图1ToolStripMenuItem_Click(object sender, EventArgs e) {

        }
    }
        
}