private void btnDuzenle_Click(object sender, EventArgs e)
        {
            Category guncelKat = new Category();

            guncelKat.CategoryName = txtKatAdi.Text;
            guncelKat.Description  = txtAciklama.Text;
            guncelKat.CategoryID   = id;
            katRep.Duzenle(guncelKat);
            dataGridView1.DataSource = katRep.Listele();
        }