Patching

I'm doing a MDI Db app using VB6 to an access backend. This is for my company, and I know that after the initial release comes out and they see how freaking cool it's turning out (much better than the DB I inherited) they are going to want alot of stuff done. Now, I have figured out a way to make the program check for updates, but I'm not quite certain I know how to apply a "patch".
From what I gather, if I don't add anything that isn't there (for instance a control that wasn't bundled with the installer, or any DLL's) that all I would need to do is copy over the new exe file. Is this the case? What if I do use a new control. Does this mean that I need to have the user un-install and re-install the program?

If you're just changed your VB 6 Application you can simple replace the old one with the new one.

If you're updating dependend components (e.g. a adding a control to a ActiveX dll) it (should) be as simple as copying over the new file, registring it (regsvr32 MyNewDLL.dll or MyNewCtrl.ocx) and restart your application.

But you should always unregister your old version of your dependend dlls/ocx (as long as no other programs use them) since this will keep your registry clean.

If you have just changed something inside a func (NOT changed its declaration) and compiled your dll/ocx binary compatible you don't need to regsvr32 it, just copy it.

But if you added something (or removed something which will break the binary compabitily) you'll need to update your exe AND your dll (inclusive regsvr32 it).

The most time you don't need to uninstall/reinstall because you know what have changed (dependency xyz.dll has been added, so you need to copy file xyz.dll and regsvr32 it), but it's always safer to create a new MSI and let the user do the uninstall/install procedure.

U can use PAtch tool by Indigo Rose Corporation.