Active records - "smart" select

[eluser]ibnclaudius[/eluser]
But this is not what I want. I need to select the communities the user MAY want to follow. So how I do select the communities that probably interest the user? I select all users from the communities he follows and check the most common communities they follow that I don't have.

I did it:

Code:

http://sqlfiddle.com/#!2/c501e/37/0

The problem is that it returns only communities that there's a user that follow another community as me. I want to show all communities that I don't follow, ordered by this "probably interest".