private void txtCMND_Leave(object sender, EventArgs e)
{
Customer customer = data.getCustomer(txtCMND.Text);
if (customer != null)
{
MessageBox.Show("Thành Công");
txtTenKhachHang.Text = customer.customerName;
txtSoDienThoai.Text = customer.phone;
dateTimePicker3.Value = customer.birthday;
khachQuen = true;
return;
}
}