How can I display summary for every 15 minutes using DATE datatype

Question

This is probably an easy question, but the answer eludes me...
I am trying to write a SQL report that displays aggregate totals for every 15 minute period. I know you can do something like this to get every minute:
select to_char(import_date,'MM-DD-YYYY HH24:MI'),
count(*) from
package_ingest
group by to_char(import_date,'MM-DD-YYYY HH24:MI')
But how can I change this query so that I get every 15 minutes?
Any feedback is greatly apprecaited!
Thanks,
-ADK

Answer 1

Hi,
GROUP BY  TRUNC (SYSDATE) + FLOOR ( (import_date - TRUNC (SYSDATE))
                                      * 24
                        * 4
                        )SYSDATE is an arbitrary reference point. It doesn't matter if import_date is earlier or later (or sometimes earlier and sometimes later).
If you want to display this in the SELECT clause, or use it in the ORDER BY clause, then repeat the expression there, or compute it once in a sub-query.
WITH  got_i_d_15     AS
     SELECT     TRUNC (SYSDATE) + FLOOR ( (import_date - TRUNC (SYSDATE))
                                           * 24
                             * 4
                             ) AS i_d_15
     FROM     package_ingest
--     WHERE     ...          -- If needed
SELECT       TO_CHAR (i_d_15, 'MM-DD-YYYY HH24:MI')     AS import_date
,       COUNT (*)                               AS cnt
FROM       got_i_d_15
GROUP BY  i_d_15
ORDER BY  i_d_15;