using System;
using System.Windows.Forms;
using System.Drawing;
using System.Data.SqlClient;

public class ex : Form
{
    private Button b1 = new Button();
    private DataGridView dgv = new DataGridView();
    int rw = 0;

    public ex()
    {
        Text = "hello";
        Width = 400;
        b1.Text = "return";
        b1.Click += new EventHandler(button_b1_click);
        b1.Location = new Point(200, 0);
        dgv.Location = new Point(0, 25);
        dgv.Height = 400;
        dgv.Width = 400;
        dgv.ColumnCount = 3;
        Controls.Add(b1);
        Controls.Add(dgv);
    }

    public void button_b1_click(object sender, EventArgs e)
    {
        SqlConnection conn = new SqlConnection("Data Source = (localdb)\\sql;" +
                                  "User id= sample_user;" +
                                  "Password = 'abc'; " +
                                  "Database = ex;");
        conn.Open();
        SqlCommand command = new SqlCommand(
                                  "select CustomerID, FirstName, LastName " +
                                  "from Customers ", conn);
        SqlDataReader reader = command.ExecuteReader();
        dgv.Columns[0].Name = "CustomerID";
        dgv.Columns[1].Name = "FirstName";
        dgv.Columns[2].Name = "LastName";
        while (reader.Read())
        {
            dgv.Rows.Add();
            dgv.Rows[rw].HeaderCell.Value = (rw + 1).ToString();
            dgv.Rows[rw].Cells[0].Value = reader[0];
            dgv.Rows[rw].Cells[1].Value = reader[1];
            dgv.Rows[rw].Cells[2].Value = reader[2];
            rw = rw + 1;
        }
        conn.Close();
    }

    [STAThread]
    static public void Main()
    {
        Application.Run(new ex());
    }
}