select Sid,count(*)as Num from t_forums a group by Sid


select b.*,c.SectionName from t_forums b,t_sections c
where b.Id=(select max(id)as Id from t_forums where Sid=c.Id)

select a.*,
       b.*,
       c.SectionName 
from t_forums b,t_sections c,
(select Sid,
       count(*)as Num 
from t_forums a 
group by Sid)a
where b.Id=(select max(id)as Id from t_forums where Sid=c.Id)
and a.sid=b.sid