Facebook application ( count friends registered )

Question

Using JS SDK for facebook, is there a way to count number of friends (of currently logged in user) that are also using my application ?? I found this query online

SELECT uid FROM user 
WHERE user.uid IN (SELECT uid2 FROM friend WHERE uid1 = ?) 
AND is_app_user = 1

But I don't understand it, and I don't know what to put instead of '?'

Thanks in advance!

Answer 1

It retrieves uid of friends of the user, specified by ?, that are also users of your application.

So instead of ? just put the current user's id.

Detailed information about: user and friend fql tables

Answer 2

In case you want to use the uid of the currently logged on user, just make use of me()