Atualizar banco de dados mysql da linha selecionada do datagridview

string cmdText = @"UPDATE t_pi_Clients
                 SET ClientName = @ClientName,
                     PostalAdd = @PostalAdd,
                     Telephone = @Telephone,
                     Fax = @Fax,
                     .... etc ....
                 WHERE ClientCode = @ClientCode";
using(MySqlConnection cn = new MySqlConnection(.....))
using(MySqlCommand cmd = new MySqlCommand(cmdText, cn))
{
    cn.Open();
    cmd.Parameters.AddWithValue("@ClientName", txtboxClientName.Text);
    cmd.Parameters.AddWithValue("@PostalAdd", txtboxPostalAddress.Text);
    ....etc etc...
    cmd.Parameters.AddWithValue("@ClientCode", textboxClientCode.Text);
    int rowsUpdated = cmd.ExecuteNonQuery();
    if(rowsUpdated > 0) 
    {
        // extract the code that loads DataGridView1 from the Form_Load
        // and create a reusable method that you could call from here
    }
}