grid view with coding in access database .net windows application with c#

first we make a function on form . this function call on page load event and after insert data query.

string str=@" ";

public void grid()

        {

            OleDbConnection con = new OleDbConnection(str);

            con.Open();

            OleDbCommand cmd = new OleDbCommand("SELECT * FROM  tablename", con);

            OleDbDataAdapter da = new OleDbDataAdapter(cmd);

            DataSet ds = new DataSet();

            da.Fill(ds);

            dataGridView1.DataSource = ds.Tables[0];

            con.Close();

        }    

  private void form_Load(object sender, EventArgs e)

        {

             grid();

        }