Grouping one year in three months

Question

I have success to grouping in one month:
SELECT      A.colo1,     TO_CHAR(A.DATA_R,'MM')||' '||TO_CHAR(A.DATA_R,'MON') MESE, sum(a.col2)
FROM xxxxxxxxx A
     WHERE ........
     GROUP BY A.colo1,TO_CHAR(A.DATA_R,'MM')||' '||TO_CHAR(A.DATA_R,'MON')
but I am looking for  a solution to grouping every three months: e.g.
q1 01/01/2007 - 31/03/2007    100  
q2 01/04/2007 - 30/06/2007    200  
q3 01/07/2007 - 30/09/2007    1500
q4 01/10/2007 - 31/12/2007    2500 Thanks in advance for any help

Answer 1

SQL> create table xxxxxxxxx
  2  as
  3  select date '2007-01-01' data_r, 50 col2 from dual union all
  4  select date '2007-02-01', 20 from dual union all
  5  select date '2007-03-01', 30 from dual union all
  6  select date '2007-04-01', 120 from dual union all
  7  select date '2007-05-01', 40 from dual union all
  8  select date '2007-06-01', 40 from dual union all
  9  select date '2007-07-01', 500 from dual union all
10  select date '2007-08-01', 700 from dual union all
11  select date '2007-09-01', 300 from dual union all
12  select date '2007-10-01', 1200 from dual union all
13  select date '2007-11-01', 200 from dual union all
14  select date '2007-12-01', 1100 from dual
15  /
Tabel is aangemaakt.
SQL> select 'q' || to_char(a.data_r,'q') q
  2       , to_char(trunc(max(a.data_r),'q'),'dd/mm/yyyy') || ' - ' || to_char(add_months(trunc(max(a.data_r),'q'),3)-1,'dd/mm/yyyy') period
  3       , sum(a.col2)
  4    from xxxxxxxxx a
  5   group by to_char(a.data_r,'q')
  6  /
Q  PERIOD                  SUM(A.COL2)
q1 01/01/2007 - 31/03/2007         100
q2 01/04/2007 - 30/06/2007         200
q3 01/07/2007 - 30/09/2007        1500
q4 01/10/2007 - 31/12/2007        2500
4 rijen zijn geselecteerd.Regards,
Rob.