using (SqlConnection conn = new SqlConnection(connectionString))
            {
                conn.Open();
                using (SqlCommand cmd =
                    new SqlCommand("UPDATE companyDB SET compname=@label3", conn))
                {
                    cmd.Parameters.AddWithValue("@label3", cmpname.Text);
                    int rows = cmd.ExecuteNonQuery();
                }


            }
        }
        catch (Exception ex)
        {
            MessageBox.Show("Not Updated");
        }

new SqlCommand("UPDATE companyDB SET compname=@label3 where id = @id", conn))