Data from DataBase to/into dgv using DataTable

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;
using System.Configuration;

namespace Feb02DataBase_DataTable
{
    public partial class Form1 : Form
    {       
        public Form1()
        {
            InitializeComponent();
            PopulatingDGV();
        }

        private void PopulatingDGV()
        {
            dataGridView1.AllowUserToAddRows = true;
            dataGridView1.RowHeadersVisible = false;

            BindingSource bs = new BindingSource();
            bs.DataSource = DAL.GetDataFromDB();
            dataGridView1.DataSource = bs;
            dataGridView1.AutoResizeColumns();
            dataGridView1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;
        }

        private void buttonSaveDB_Click(object sender, EventArgs e)
        {
            BindingSource bs = (BindingSource)dataGridView1.DataSource;
            DataTable dt1 = (DataTable)bs.DataSource;
            DAL.UpdateDataInDB(dt1);
        }
    }

    public class DAL
    {
        private static string connString = ConfigurationManager.ConnectionStrings["Feb01TestConnectionString"].ConnectionString;

        public static DataTable GetDataFromDB()
        {
            DataTable table = new DataTable("customers");
            using (SqlConnection sqlConn = new SqlConnection(connString))
            {
                using (SqlCommand cmd = new SqlCommand())
                {
                    cmd.CommandText = "select_GetCustomers";//SELECT * FROM Customers
                    cmd.CommandType = CommandType.StoredProcedure;  //if you use CommandType.Text;
                    cmd.Connection = sqlConn;
                    using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                        da.Fill(table);
                }
            }
            return table;
        }

        public static void UpdateDataInDB(DataTable table)
        {
            using (SqlConnection sqlConn = new SqlConnection(connString))
            {
                using (SqlCommand cmd = new SqlCommand())
                {
                    cmd.CommandText = "select_GetCustomers";
                    cmd.CommandType = CommandType.StoredProcedure;
                    cmd.Connection = sqlConn;
                    sqlConn.Open();
                    using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                    {
                        using (SqlCommandBuilder cb = new SqlCommandBuilder(da))
                        {
                            da.UpdateCommand = cb.GetUpdateCommand();
                            da.Update(table);
                        }
                    }
                }
            }
        }
    }
}

Hope it helps,
Mitja