[excel] Save multiple sheets to .pdf

I have a reporting spreadsheet that grabs some data from a database and forms three sheets of summary report information. I want to run the spreadsheet automatically from the command line, and have it automatically save all three reporting sheets as a PDF file(s).

At first I thought I could have a VBA macro on the sheet do this by a series of "print as PDF", but that requires an intermediary interactive dialog box to specify the output file name. Then I find that I can just save as pdf, and the macro can set the output file name. However this creates three separate files, and I have to then later put them together externally to merge them.

(It is odd that save as pdf only saves one sheet, where other save modes seem to save the entire workbook.)

Yes, there are tools for merging the three files later, but I want to know if there is some easy way to get Excel to save multiple sheets together as one pdf file.

I print now by a series of things like:

ActiveSheet.ExportAsFixedFormat Type:=xlTypePDF, ...

Could I do instead a single statement something like (pseudo-code):

ThisWorkbook.Sheets(1,2,3,4).ExportAsFixedFormat Type:=xlTypePDF, ...

Similar to Tim's answer - but with a check for 2007 (where the PDF export is not installed by default):

Public Sub subCreatePDF()

    If Not IsPDFLibraryInstalled Then
        'Better show this as a userform with a proper link:
        MsgBox "Please install the Addin to export to PDF. You can find it at http://www.microsoft.com/downloads/details.aspx?familyid=4d951911-3e7e-4ae6-b059-a2e79ed87041". 
        Exit Sub
    End If

    ActiveSheet.ExportAsFixedFormat Type:=xlTypePDF, _
        Filename:=ActiveWorkbook.Path & Application.PathSeparator & _
        ActiveSheet.Name & " für " & Range("SelectedName").Value & ".pdf", _
        Quality:=xlQualityStandard, IncludeDocProperties:=True, _
        IgnorePrintAreas:=False, OpenAfterPublish:=True
End Sub

Private Function IsPDFLibraryInstalled() As Boolean
'Credits go to Ron DeBruin (http://www.rondebruin.nl/pdf.htm)
    IsPDFLibraryInstalled = _
        (Dir(Environ("commonprogramfiles") & _
        "\Microsoft Shared\OFFICE" & _
        Format(Val(Application.Version), "00") & _
        "\EXP_PDF.DLL") <> "")
End Function

I recommend adding the following line after the export to PDF:

ThisWorkbook.Sheets("Sheet1").Select

(where eg. Sheet1 is the single sheet you want to be active afterwards)

Leaving multiple sheets in a selected state may cause problems executing some code. (eg. unprotect doesn't function properly when multiple sheets are actively selected.)

In Excel 2013 simply select multiple sheets and do a "Save As" and select PDF as the file type. The multiple pages will open in PDF when you click save.