private void dataGridView1_RowValidated(object sender, DataGridViewCellEventArgs e)
        {
            int    yazarID = Convert.ToInt32(dataGridView1.CurrentRow.Cells[0].Value);
            string adi     = dataGridView1.CurrentRow.Cells[1].Value.ToString();

            Islemler.GuncelleYazar(yazarID, adi);
        }