SUM Parenthesis - Difference???

Question

Hi;
i just want to ask if there is any differences between calculating summuation inside the pharenthesis or not???
Example Query;
select     a12.CATEGORY,
     (sum(a11.COL1) / (CASE WHEN COL2=0 THEN NULL ELSE COL2 END)) SUM1,
     sum((a11.COL1 / (CASE WHEN COL2=0 THEN NULL ELSE COL2 END))) SUM2
from     table1     a11,
     table2a12
where     a11.ID = a12.ID
group by     a12.CATEGORY
Which one is faster? SUM1 or SUM2 or no difference???
Note that DB is Oracle 10g.
Thanks...

Answer 1

It makes no difference because the query won't work anyway. COL1 is aggregated but COL2 isn't...
SQL> ed
Wrote file afiedt.buf
  1  with t as (select 4 as col1, 2 as col2 from dual union all
  2             select 5, 3 from dual union all
  3             select 6, 0 from dual union all
  4             select 7, 3 from dual)
  5  --
  6  select sum(col1) / (case when col2=0 then null else col2 end) as sum1
  7        ,sum(col1 / case when col2=0 then null else col2 end) as sum2
  8* from t
SQL> /
select sum(col1) / (case when col2=0 then null else col2 end) as sum1
ERROR at line 6:
ORA-00937: not a single-group group function