private void simpleButton2_Click(object sender, EventArgs e)
{
QuetRFID mau = new QuetRFID();
mau.ShowDialog();
while (mau.Visible == true)
{
}
DS.Tables[0].Rows.Add(Convert.ToInt32(txtMaNV.Text), txtHoten.Text, cbBopHan.Text, cbChucVu.Text, mathe);
connection.Open();
update = new MySqlCommandBuilder(mySqlDataAdapter);
mySqlDataAdapter.Update(DS, "lvtn.nhanvien");
}