Rownum and group by syntax error

Question

Hi,
I have a query, which use Oracle rownum.
if I put the group by clause to inner select clause, it does not work.
select PS1.PO_ID, PS1.PO_DATE, PS1.POD_PO_ID, sum(PO_ID)
from ( select rownum r_ , A.PO_ID, A.PO_DATE, B.POD_PO_ID
from OPS$RS3.DTINV_PO_DETAIL B, OPS$RS3.DTINV_PO A
where (A.PO_ID <= '450')
group by A.PO_ID, A.PO_DATE,B.POD_PO_ID
) PS1
where r_ > 0 AND r_ <= 10
but if I put the group by clause outside, it work. but this is not what I want.
select PS1.PO_ID, PS1.PO_DATE, PS1.POD_PO_ID, sum(PO_ID)
from ( select rownum r_ , A.PO_ID, A.PO_DATE, B.POD_PO_ID
from OPS$RS3.DTINV_PO_DETAIL B, OPS$RS3.DTINV_PO A
where (A.PO_ID <= '450')
) PS1
where r_ > 0 AND r_ <= 10
group by A.PO_ID, A.PO_DATE,B.POD_PO_ID
Can anybody explain why?
Thanks!
xiong

Answer 1

select PS1.PO_ID
      ,PS1.PO_DATE
      ,PS1.POD_PO_ID
      ,sum(PO_ID)
from  (select rownum r_
             ,A.PO_ID
             ,A.PO_DATE
             ,B.POD_PO_ID
       from   OPS$RS3.DTINV_PO_DETAIL B
             ,OPS$RS3.DTINV_PO A
       where (A.PO_ID <= '450')
       group  by A.PO_ID
                ,A.PO_DATE
                ,B.POD_PO_ID
      ) PS1
where r_ > 0 AND r_ <= 10I don't get what you're trying to do here.
First of all, you have no join condition between the A and B tables of your inline view. That's a cartesian product, probably not what you want.
Also, why do you have '450' in quote marks? Is a.po_id a varchar2 column?
You can't do a GROUP BY like this with rownum in your select list. It doesn't make any sense.
Why do you want row numbers between 1 and 10? Those are just 10 arbitrary rows not based on anything. Or is that what you want?