for the feedback... about jomsocial vs groupjive, we are using integration of moodle with joomla for our student community.. Moodle.. to integrate to joomla we need to use joomdle. Joomdle have only integration capacities with jomsocial.. not with groupjive...
Their feature page says they support CB. I guess there's some sort of special feature in it to support Jomsocial groups? I'd be glad to work with them in supporting GJ if this is the case if they'd like to contact us directly.
ANd to be honest.. the design of the template of jomsocial is nicer and more ergonomic to integrate in our clarion rocket theme....
All I can say regarding this is we're certainly working to improve the frontend (and backend) appearance of CB with release of CB 2.0 (jquery, bootstrap, and HTML5 based). GJ will become a part of CB 2.0s core features as well. Currently though GJ frontend is entirely template based so it's possible to restyle it to fit your template.
about "CB Query Field to query", is there a kind of documentation for help ???
Nope. Most professional plugins don't come with documentation. If we have anything on them it'd be in our tutorials below.
www.joomlapolis.com/support/tutorials
Once installed and enabled you'd navigate to CB > Field Management. Then click "New" and create a new field of the type "Query". You then supply you database SELECT query for the value you're wanting. Substitutions are also supported in your query (e.g. [user_id]).