private void btnTaoKHMoi_Click(object sender, EventArgs e)
{
AddKhachHang addKhachHang = new AddKhachHang();
addKhachHang.ShowDialog();
UpdateDanhSachKH();
}
//-------------------------------------------------------------thêm_nhân_viên----------------------------------------------------------//
private void btnThemKH_Click(object sender, EventArgs e)
{
button_save.PerformClick();
AddKhachHang kh = new AddKhachHang(this);
kh.ShowDialog();
UpdateKhachHang();
}