[SQLObject] Handling upgrades involving database changes?

[Leif K-B. <eu...@ec...>]

I'm developing a web web application project which uses SQLObject for 
the database connection. Everything's working great on my test system; 
however, looking into the future, I can see that my project will have 
updates released at some point, some of which will probably involve 
changes to the database schema.

If everyone upgraded straight from version A to version B, it would be 
very simple: release a script that alters the database along with every 
version and have the users run it. Unfortunately, some people will end 
up going from version A straight to version D, which would end up giving 
them a messed up database schema.

How do other people handle upgrades to database schemas gracefully?