private async void mtrBtnDuzenle_Click(object sender, EventArgs e)
        {
            Musteriler obj = musterilerBindingSource.Current as Musteriler;

            if (obj != null)
            {
                using (FormMusteriEkleDuzenle frm = new FormMusteriEkleDuzenle(obj))
                {
                    if (frm.ShowDialog() == DialogResult.OK)
                    {
                        try
                        {
                            musterilerBindingSource.EndEdit();
                            await db.SaveChangesAsync();
                        }
                        catch (Exception ex)
                        {
                            MessageBox.Show(ex.Message, "Mesaj", MessageBoxButtons.OK, MessageBoxIcon.Error);
                        }
                    }
                }
            }
        }