private void capNhatSach_Load(object sender, EventArgs e)
{
dtpNgayNhap.Format = DateTimePickerFormat.Custom;
dtpNgayNhap.CustomFormat = "dd-MM-yyyy";
connectSer.Connect();
sachSer.getAll(dgvSach);
connectSer.LoadDataCombobox(cbMaLinhVuc, "select MALV from tblLinhVuc");
connectSer.LoadDataCombobox(cbTenLinhVuc, "select TENLV from tblLinhVuc");
}