Exporting SQL db to an Excel issue

Question

I'm trying to set up a button to easily export the database in my app to an excel sheet. However I'm having issues getting it to work. And I cant figure out what's going wrong, since I'm not seeing any errors.

 {
            string cs = @"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\Database1.mdf";
            SqlConnection con = new SqlConnection(cs);
            con.Open();
            SqlCommand command = new SqlCommand("SELECT * FROM AvSites", con);
            SqlDataAdapter dataadpter = new SqlDataAdapter(command);
            DataTable datatable = new DataTable("AvSites");
            dataadpter.Fill(datatable);
            datatable.WriteXml(Application.StartupPath + "AvSitesDbExport.xlsx");
            MessageBox.Show("export data");

        }

When I run the app in debug mode, the button creates a xml (xlsx) file on my desktop, which I guess is okay ? since its in debug mode, not sure what rules apply here.

But if I publish the app, I dont see the file being created anywhere.

Am I doing something wrong ? Application.StartupPath should return the dir from which the .exe is executed, right ?

Answer 1

 {
            string cs = @"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\Database1.mdf";
            SqlConnection con = new SqlConnection(cs);
            con.Open();
            SqlCommand command = new SqlCommand("SELECT * FROM AvSites", con);
            SqlDataAdapter dataadpter = new SqlDataAdapter(command);
            DataTable datatable = new DataTable("AvSites");
            WriteExcelWithNPOI(datatable,"xls")  /* "xls" or "xlsx"
            MessageBox.Show("export data");

        }
public void WriteExcelWithNPOI(DataTable dt, String extension)
      {           
          IWorkbook workbook;          

          if (extension == "xlsx") {
              workbook = new XSSFWorkbook();                
          }
          else if (extension == "xls")
          {
              workbook = new HSSFWorkbook();
          }
          else {
              throw new Exception("This format is not supported");
          }

          ISheet sheet1 = workbook.CreateSheet("Sheet 1");

          //make a header row
          IRow row1 = sheet1.CreateRow(0);

          for (int j = 0; j < dt.Columns.Count; j++)
          {

              ICell cell = row1.CreateCell(j);
              String columnName = dt.Columns[j].ToString();
              cell.SetCellValue(columnName);
          }

          //loops through data
          for (int i = 0; i < dt.Rows.Count; i++)
          {
              IRow row = sheet1.CreateRow(i + 1);
              for (int j = 0; j < dt.Columns.Count; j++)
              {

                  ICell cell = row.CreateCell(j);
                  String columnName = dt.Columns[j].ToString();
                  cell.SetCellValue(dt.Rows[i][columnName].ToString());
              }
          }

          using (var exportData = new MemoryStream())
          { 
              Response.Clear();                
              workbook.Write(exportData);
              if (extension == "xlsx") //xlsx file format
              {
                  Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                  Response.AddHeader("Content-Disposition", string.Format("attachment;filename={0}", "ContactNPOI.xlsx"));                   
                  Response.BinaryWrite(exportData.ToArray());             
              }
              else if (extension == "xls")  //xls file format
              { 
                  Response.ContentType = "application/vnd.ms-excel";
                  Response.AddHeader("Content-Disposition", string.Format("attachment;filename={0}", "ContactNPOI.xls"));
                  Response.BinaryWrite(exportData.GetBuffer());
              }   
              Response.End();
          }
      }