Ado.NET Adapter

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 WFA
{
    public partial class Form1 : Form
    {
        SqlConnection con = new SqlConnection();
        SqlDataAdapter adapter;
        DataSet ds;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            con.ConnectionString = "Server=LAB-418-08-PC\\STUDENT; database=TestBase; Integrated Security=true;";
            try
            {
                con.Open();
                SqlCommand command = new SqlCommand("SELECT * FROM Users");
                adapter = new SqlDataAdapter("SELECT * FROM Users", con);
                SqlCommandBuilder commandBuilder = new SqlCommandBuilder(adapter);
                ds = new DataSet();
                adapter.Fill(ds, "c");
                dataGridView1.DataSource = ds.Tables["c"];
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString(), "Exception message");
            }
            finally
            {
                con.Close();
            }
        }

        private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            dataGridView1.BeginEdit(true);
        }

        private void dataGridView1_CellLeave(object sender, DataGridViewCellEventArgs e)
        {
            dataGridView1.EndEdit();
            adapter.Update(ds, "c");
        }
    }
}