Aggregate rows with count and add fraction of whole result set sum

Question

Here's the explaination by example
# Source table
ID | TYPE
1 | A
2 | A
3 | B
4 | C
5 | C
6 | A
7 | C
8 | A
Now, I'm aggregating and counting:
TYPE | count(*)
A | 4
B | 1
C | 3
I need to assign to row also an information about the fraction of overall sum of rows, so simply divide each count by 8 (in that case), so the result is:
TYPE | frac
A | 0.5
B | 0.125
C | 0.375
Is it possible to do this in NOT nested query, using some Oracle function?
Edited by: Wojtus-J on Feb 18, 2011 5:47 AM

Answer 1

Why can you not use a subquery?
SQL> with test_data as
  2      (
  3      select 'A' x from dual union all
  4      select 'A' x from dual union all
  5      select 'B' x from dual union all
  6      select 'C' x from dual union all
  7      select 'C' x from dual union all
  8      select 'A' x from dual union all
  9      select 'C' x from dual union all
10      select 'A' x from dual
11      )
12  select
13      x,
14      ratio_to_report(count(*)) over (partition by null)
15  from
16      test_data
17  group by
18      x;
X RATIO_TO_REPORT(COUNT(*))OVER(PARTITIONBYNULL)
A                                             .5
B                                           .125
C                                           .375
SQL>