private void cbSiniflar_SelectedIndexChanged(object sender, EventArgs e)
{
txtSinifAd.Text = cbSiniflar.SelectedItem.ToString();
Sinif s = new Sinif();
txtSinifID.Text = s.SinifIDGetir(txtSinifAd.Text).ToString();
}
private void cbSiniflar_SelectedIndexChanged(object sender, EventArgs e)
{
Sinif s = new Sinif();
txtSinifAdi.Text = cbSiniflar.SelectedItem.ToString();
txtSinifID.Text = s.SinifIDGetir(txtSinifAdi.Text).ToString();
txtMarkaID.Clear();
txtMarkaAd.Clear();
cbMarkalar.Items.Clear();
Marka m = new Marka();
m.MarkalariGetir(cbMarkalar, Convert.ToInt32(txtSinifID.Text));
}