As far as I know, the only thing you need to change is database.yaml.
So I set up it, changing adapter from mysql to sqlite and pointing to
the file, which should play a role of database. Now when I try to run
rake db:create an error pops up saying "Could not find table 'users'".
Why's that and how to override this? By logic, db:create is only
creating a blank database, without any table in it. So, what's the
deal with tables then?
The reason why rake aborted was that the environment.rb had some
observers set up. It seems that these observers tried to communicate
with a model, which table had not been created. That's how it should
be though - you can't have a table for a model in the database, if you
don't have the database. And the error occurred when I was trying to
run rake db:create. So, it seems now that the only solution is to
comment observers in the environment.rb before creating the database
and comment them when the database is created, which is a little
stupid - who knows how much times I would need to drop database and
create it again and now I need to comment and uncomment observers each
time?