How to append datatable to an exist excel file?

Aug 12, 2014 at 4:34 AM
I have to write a datatable into an exist excel file which is not empty, the columns of the datatable and the sheet of the file are the same, how can I do this? I tried the append mode, like this:
            FileStream file = new FileStream(FileName, FileMode.Append);
            hssfworkbook.Write(file);
but nothing happens, Is there anything wrong? Thank you.