private void HienThi()
{
dgvDTNam.DataSource = Bus.DT("SELECT YEAR(NgayXuat) AS NAM ,SUM(ThanhTien) AS DOANHTHU FROM dbo.HoaDonXuat INNER JOIN dbo.ChiTietHoaDonXuat ON ChiTietHoaDonXuat.MaHDX = HoaDonXuat.MaHoaDon WHERE TrangThai=N'Đã thanh toán' GROUP BY YEAR(NgayXuat)");
dgvDTNam.AutoResizeColumns();
}