What is the best way to notify a user that updates are available in a desktop application?

I have a Windows desktop application that is used as the front-end for a webservice. This application has a database that could get updated from time to time, but it would also work with an old database. I want my application to do a background check on startup, whether the database needs to be updated.

If that is the case, I want to notify the user.

Question:

What are the best ways to show the user a notification for available updates on a desktop application ?