Using dpkg to install upgrade and dist-upgrade packages

So I'm playing around with offline package installation on 12.04 Server, having downloaded packages by retrieving and wgetting their URIs using the instructions here: http://www.webupd8.org/2009/11/get-list-of-packages-and-dependencies.html

I did this with apt-get upgrade and apt-get dist-upgrade, then went about installing the downloaded packages using dpkg -i. So the process looked like so:

1. Get URIs
2. wget the packages to a folder (upgrade packages to /upgrade and dist-upgrade packages to /dist-upgrade)
3. run dpkg -i /upgrade/*.deb and then dpkg -i /dist-upgrade/*.deb

My question is: would this method of manually installing the updated packages correctly get everything updated, giving the same result as if I'd just run apt-get upgrade and apt-get dist-upgrade normally? Or is there something that the normal apt-get commands do that wouldn't get done with this way?

Instead of using dpkg, which is a low level package manager, you'd be better off using apt. To install the .deb files using apt, copy them to the apt cache

sudo cp *.deb /var/cache/apt/archives/

and then just do the regular upgrade:

apt-get upgrade

The apt command will use the files in its cache rather than downloading it off the net, so that pretty much serves your purpose.