How to use "Rank" function in Oracle?

Question

I need to display Top 15 records by using rank function.
Here is my query...I need to pull top 15 FAQ's using the below query.. How can I use RANK function to display the Top 15 FAQ"s in the list.
Select  distinct SUb1.FAQ,Sub1.FAQ_Hits,GU.display_Name_FMLS as displayname,ev.ParentLinkrecordid,ev.userid from User GU
Join Event ev
ON LOWER (ev.userid) IN (LOWER (GU.lanid), LOWER (Gu.racfid))
Join (Select distinct sm.stem as FAQ,Sum(ev.Eventresults) as FAQ_Hits,ev.ParentLinkrecordid as Topic_ID from Event ev
Join SubjectMatter sm
ON (TO_CHAR (sm.smrecordid) = ev.eventdetail1) AND ev.eventdetail1 IS NOT NULL AND sm.smtype = 1
Where (Upper(ev.eventsubtype) in (Upper('FAQ'),Upper('OPENFAQ')))
AND TO_DATE (eventdatetime, 'yyyy-mm-dd hh24:mi:ss') >= TO_DATE ('20100601', 'yyyymmdd')
and TO_DATE (eventdatetime, 'yyyy-mm-dd hh24:mi:ss') <= TO_DATE ('20100831', 'yyyymmdd')
Group by sm.stem,ev.Parentlinkrecordid
order by FAQ )sub1
ON Sub1.Topic_ID = ev.ParentLinkrecordid)

Answer 1

A few bits that I noticed in the query ...
in (Upper('FAQ'),Upper('OPENFAQ'))1) Do you really a upper for a string which is already in upper case.
Select distinct sm.stem as FAQ,Sum(ev.Eventresults) as FAQ_Hits,ev.ParentLinkrecordid as Topic_ID2) Do you need a distinct when you are using a GROUP function viz. SUM ?
You rank query is as follows, I am not very good at the ANSI style JOIN so changed it slightly ... :-)
Also notice the usage rank function in the "sub1" query.
select distinct sub1.faq,
                sub1.faq_hits,
                gu.display_name_fmls as displayname,
                ev.parentlinkrecordid,
                ev.userid
from user gu, event ev,
  (select rank() over (order by sum(ev.eventresults) desc) rnk,
          sum(ev.eventresults) as faq_hits,
          sm.stem as faq,         
          ev.parentlinkrecordid as topic_id
     from event ev, subjectmatter sm
    where (to_char(sm.smrecordid) = ev.eventdetail1)
      and ev.eventdetail1 is not null
      and sm.smtype = 1
      AND upper(ev.eventsubtype) in ('FAQ', 'OPENFAQ')
      and to_date(eventdatetime, 'yyyy-mm-dd hh24:mi:ss') >= to_date('20100601', 'yyyymmdd')
      and to_date(eventdatetime, 'yyyy-mm-dd hh24:mi:ss') <= to_date('20100831', 'yyyymmdd')
    group by sm.stem, ev.parentlinkrecordid
    order by faq) sub1
where lower(ev.userid) in (lower(gu.lanid), lower(gu.racfid))
  and sub1.topic_id = ev.parentlinkrecordid)
  and sub1.rnk <= 15;Like mentioned above, some sample data would have helped.