How to create excel file with multiple sheets from DataSet using C#

Here is a simple C# class that programatically creates an Excel WorkBook and adds two sheets to it, and then populates both sheets. Finally, it saves the WorkBook to a file in the application root directory so that you can inspect the results...

public class Tyburn1
{
    object missing = Type.Missing;
    public Tyburn1()
    {
        Excel.Application oXL = new Excel.Application();
        oXL.Visible = false;
        Excel.Workbook oWB = oXL.Workbooks.Add(missing);
        Excel.Worksheet oSheet = oWB.ActiveSheet as Excel.Worksheet;
        oSheet.Name = "The first sheet";
        oSheet.Cells[1, 1] = "Something";
        Excel.Worksheet oSheet2 = oWB.Sheets.Add(missing, missing, 1, missing) 
                        as Excel.Worksheet;
        oSheet2.Name = "The second sheet";
        oSheet2.Cells[1, 1] = "Something completely different";
        string fileName = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)        
                                + "\\SoSample.xlsx";
        oWB.SaveAs(fileName, Excel.XlFileFormat.xlOpenXMLWorkbook,
            missing, missing, missing, missing,
            Excel.XlSaveAsAccessMode.xlNoChange,
            missing, missing, missing, missing, missing);
        oWB.Close(missing, missing, missing);
        oXL.UserControl = true;
        oXL.Quit();
    }
}

To do this, you would need to add a reference to Microsoft.Office.Interop.Excel to your project (you may have done this already since you are creating one sheet).

The statement that adds the second sheet is...

Excel.Worksheet oSheet2 = oWB.Sheets.Add(missing, missing, 1, missing) 
                            as Excel.Worksheet;

the '1' argument specifies a single sheet, and it can be more if you want to add several sheets at once.

Final note: the statement oXL.Visible = false; tells Excel to start in silent mode.