Getting running total of the count

Question

select a,count(*),sum(count(*)) over (partition by a)
from t group by a order by 2.
The query is giving me results like this given below.
A Count Sum Count(*)
a1     1 1
a2     1 1
a3     2     2
a4     2     2
a5     3     3
Instead I require result like
A Count Sum Count(*)
a1     1     1
a2     1     2
a3     2     4
a4     2     6
a5     3     9

Answer 1

SQL> create table t
  2  as
  3  select 'a1' a from dual union all
  4  select 'a2' from dual union all
  5  select 'a3' from dual union all
  6  select 'a3' from dual union all
  7  select 'a4' from dual union all
  8  select 'a4' from dual union all
  9  select 'a5' from dual union all
10  select 'a5' from dual union all
11  select 'a5' from dual
12  /
Tabel is aangemaakt.
SQL> select a
  2       , count(*)
  3       , sum(count(*)) over (partition by a)
  4    from t
  5   group by a
  6   order by 2
  7  /
A    COUNT(*) SUM(COUNT(*))OVER(PARTITIONBYA)
a1          1                               1
a2          1                               1
a3          2                               2
a4          2                               2
a5          3                               3
5 rijen zijn geselecteerd.
SQL> select a
  2       , count(*)
  3       , sum(count(*)) over (order by a)
  4    from t
  5   group by a
  6   order by 2
  7  /
A    COUNT(*) SUM(COUNT(*))OVER(ORDERBYA)
a1          1                           1
a2          1                           2
a3          2                           4
a4          2                           6
a5          3                           9
5 rijen zijn geselecteerd.Regards,
Rob.