string a1 = dataGridView4.Rows[0].Cells[0].Value.ToString();
                string a2 = dataGridView4.Rows[0].Cells[1].Value.ToString();
                string a3 = dataGridView4.Rows[0].Cells[2].Value.ToString();
                string a4 = dataGridView4.Rows[0].Cells[3].Value.ToString();



                MySqlCommand command = con.CreateCommand();
                command.CommandText = "update druzyny  set ID_t='" + a2 + "',nazwa_d='" + a3 + "',punkty_d='" + a4 + "' where id_d='" + a1 + "';";
                con.Open(); //open the connection
                command.ExecuteNonQuery();