' Windows Installer utility to generate a transform from two databases
' For use with Windows Scripting Host, CScript.exe or WScript.exe
' Copyright (c) Microsoft Corporation. All rights reserved.
' Demonstrates use of Database.GenerateTransform and MsiDatabaseGenerateTransform
'
Option Explicit

Const msiOpenDatabaseModeReadOnly     = 0
Const msiOpenDatabaseModeTransact     = 1
Const msiOpenDatabaseModeCreate       = 3

If Wscript.Arguments.Count < 2 Then
	Wscript.Echo "Windows Installer database tranform generation utility" &_
		vbNewLine & " 1st argument is the path to the original installer database" &_
		vbNewLine & " 2nd argument is the path to the updated installer database" &_
		vbNewLine & " 3rd argument is the path to the transform file to generate" &_
		vbNewLine & " If the 3rd argument is omitted, the databases are only compared" &_
		vbNewLine &_
		vbNewLine & "Copyright (C) Microsoft Corporation.  All rights reserved."
	Wscript.Quit 1
End If

' Connect to Windows Installer object
On Error Resume Next
Dim installer : Set installer = Nothing
Set installer = Wscript.CreateObject("WindowsInstaller.Installer") : CheckError

' Open databases and generate transform
Dim database1 : Set database1 = installer.OpenDatabase(Wscript.Arguments(0), msiOpenDatabaseModeReadOnly) : CheckError
Dim database2 : Set database2 = installer.OpenDatabase(Wscript.Arguments(1), msiOpenDatabaseModeReadOnly) : CheckError
Dim transform:transform = ""  'Simply compare if no output transform file supplied
If Wscript.Arguments.Count >= 3 Then transform = Wscript.Arguments(2)
Dim different:different = Database2.GenerateTransform(Database1, transform) : CheckError
If Not different Then Wscript.Echo "Databases are identical" Else If transform = Empty Then Wscript.Echo "Databases are different"

Sub CheckError
	Dim message, errRec
	If Err = 0 Then Exit Sub
	message = Err.Source & " " & Hex(Err) & ": " & Err.Description
	If Not installer Is Nothing Then
		Set errRec = installer.LastErrorRecord
		If Not errRec Is Nothing Then message = message & vbNewLine & errRec.FormatText
	End If
	Wscript.Echo message
	Wscript.Quit 2
End Sub