Activerecord group by Query

One day, I need use "group by" query,
But I don't know how to write it on activerecord,

I try mony method, but I can't get the results. I am also post a thread to Forum of caslte, but no one replay it, may be it is so easy.
So, I redo my work. I found,
I can use

"Select Table. Name, count (table. Name) from Table group by table. Name order by table count (table. Name) DESC"

My gold, is correct now.

Hqlbasedquery query = new hqlbasedquery (typeof (activityinfo), hql );
Return executequery (query );

How to get the data? Like below

Arraylist list = O as arraylist;
For (INT I = 0; I <list. Count; I ++)
{
Object [] list2 = list [I] as object [];
}

And I found in activerecord you can use SQL language to query, just set querylanguage to SQL,

Anthor method: navtie queryisessionfactoryholder sessionholder = activerecordmediator. getsessionfactoryholder (); isession session = sessionholder. createsession (typeof (Synonym); try {string query = ""; IQUERY sqlquery = session. createsqlquery (query, "synonym", typeof (Synonym); sqlquery. setmaxresults (10); Return sqlquery. list ();} finally {sessionholder. releasesession (session );}