Export Excel in Dynamics 365 for finance and operation

using System.IO;   

using OfficeOpenXml;

using OfficeOpenXml.Style; 

using OfficeOpenXml.Table;

class VendInvoiceXLExportMatch

{

    public static void main(Args _args)

    {

        VendInvoiceInfoTable        localVendInvoiceInfoTable;

        

        VendInvoiceXLExportMatch ExportMatch = new VendInvoiceXLExportMatch();

        if(!localVendInvoiceInfoTable.Num)

            throw error("Invoice number must be filled in");

        localVendInvoiceInfoTable = _args.record();

        

        ExportMatch.Export(localVendInvoiceInfoTable);

    }

    public void Export(VendInvoiceInfoTable        _localVendInvoiceInfoTable)

    {

        VendInvoiceInfoLine vendInvoiceInfoLine;  

        MemoryStream memoryStream = new MemoryStream();

        using (var package = new ExcelPackage(memoryStream))  

        {

            var currentRow = 1;

            var worksheets = package.get_Workbook().get_Worksheets();

            var CustTableWorksheet = worksheets.Add("Export Invoice Data Matching");

            var cells = CustTableWorksheet.get_Cells();

            OfficeOpenXml.ExcelRange cell = cells.get_Item(currentRow, 1);

            System.String value = "PurchId";

            cell.set_Value(value);

            cell = null;

            value = "ItemId";

            cell = cells.get_Item(currentRow, 2);

            cell.set_Value(value);

            value = "Qty";

            cell = cells.get_Item(currentRow, 3);

            cell.set_Value(value);

            value = "PurchPrice";

            cell = cells.get_Item(currentRow, 4);

            cell.set_Value(value);

            value = "LineAmount";

            cell = cells.get_Item(currentRow, 5);

            cell.set_Value(value);

            //Get Data in to Excel

            while select OrigPurchId,ItemId,ReceiveNow,PurchPrice,LineAmount from vendInvoiceInfoLine

                where vendInvoiceInfoLine.ParmId == _localVendInvoiceInfoTable.ParmId

                    && vendInvoiceInfoLine.TableRefId == _localVendInvoiceInfoTable.TableRefId

            {

                currentRow ++;

                cell = null;

                cell = cells.get_Item(currentRow, 1); 

                cell.set_Value(vendInvoiceInfoLine.OrigPurchId);

                cell = null;              

                cell = cells.get_Item(currentRow, 2); 

                cell.set_Value(vendInvoiceInfoLine.ItemId);

                cell = null;

                cell = cells.get_Item(currentRow, 3);

                cell.set_Value(vendInvoiceInfoLine.ReceiveNow);

                cell = null;

                cell = cells.get_Item(currentRow, 4);

                cell.set_Value(vendInvoiceInfoLine.PurchPrice);

                cell = null;

                cell = cells.get_Item(currentRow, 5);

                cell.set_Value(vendInvoiceInfoLine.LineAmount);

            }

            package.Save(); 

            file::SendFileToUser(memoryStream, strFmt('Invoice:%1',_localVendInvoiceInfoTable.Num));

        }

    }

}