private void button2_Click(object sender, EventArgs e)
{
EntityOgrenci ent = new EntityOgrenci();
ent.AD = txtograd.Text;
ent.SOYAD = txtogrsoyad.Text;
ent.FOTOGRAF = txtogrfotograf.Text;
ent.KULUPID = Convert.ToInt32(cmbogrkulup.SelectedValue);
BLLOgrenci.EKLE(ent);
OgrenciListesi();
}