Export dataset to the excel sheet in asp.net c#
First of all your function start streaming content
Response.ContentType = "application/vnd.ms-excel";
Response.AppendHeader("Content-Disposition", "attachment; filename=" + filename + "");
to end user and END it with
Response.End();
Moreover if you fix this your code will product 4 excel files.
There is an existing code for creating Excel sheets on stack overflow: How to add additional worksheets to an Excel from DataTable The only change you will have to made will be saving xlsx to stream and transmit this stream to user.