private void btnExportOrder_Click(object sender, EventArgs e)
        {
            ReportToExcel excel = new ReportToExcel();

            DataTable dt = (DataTable)dtgvOrderList.DataSource;

            excel.ExportOrder(dt, "Đặt hàng", "DANH SÁCH ĐƠN ĐẶT HÀNG");
        }
        private void btnExportWarranty_Click(object sender, EventArgs e)
        {
            ReportToExcel excel = new ReportToExcel();

            DataTable dt = (DataTable)dtgvWarrantyBillList.DataSource;

            excel.ExportWarranty(dt, "Bảo hành", "DANH SÁCH BẢO HÀNH");
        }
        private void btnExportRepurchase_Click(object sender, EventArgs e)
        {
            ReportToExcel excel = new ReportToExcel();

            DataTable dt = (DataTable)dtgvRepurchaseList.DataSource;

            excel.ExportRepuchase(dt, "Mua lại", "DANH SÁCH HÀNG MUA LẠI");
        }
        private void btnExportSales_Click(object sender, EventArgs e)
        {
            ReportToExcel excel = new ReportToExcel();

            DataTable dt = (DataTable)dtgvSellingBillList.DataSource;

            excel.ExportSales(dt, "Bán hàng", "DANH SÁCH HÀNG BÁN");
        }
        private void btnExportImporting_Click(object sender, EventArgs e)
        {
            ReportToExcel excel = new ReportToExcel();

            DataTable dt = (DataTable)dtgvImportingBillList.DataSource;

            excel.ExportImporting(dt, "Nhập hàng", "DANH SÁCH NHẬP HÀNG");
        }