Hi ,
you can use GROUP BY , at the expense of adding one more column of SERIAL data type,
say,
select * from t_a limit 10;
access_log=# SELECT * from t_a limit 15;
sno | value
-----+------- 1 | 4533 2 | 2740 3 | 9970
4 | 6445 5 | 2220 6 | 2301
7 | 6847 8 | 5739 9 | 5286
10 | 5556 11 | 9309 12 | 9552
13 | 8589 14 | 5935 15 | 2382
(15 rows)
if you want avg for every third item you can use:
access_log=# SELECT avg(value) from t_a group by (1+(sno-1)/3) limit 5;
avg
-----------------5747.66666666673655.33333333335957.33333333338139.00000000005635.3333333333
(5 rows)
you can replace 3 in the SQL with any number for grouping that many records.
if you need MEAN , STDDEV , MAX, MIN etc you can use approprite AGGREGATE that PGSQL supports
for numbers eg for MAX
access_log=# SELECT MAX(value) from t_a group by (1+(sno-1)/3) limit 5;max
------99706445684795528589
(5 rows)
Regds
MAlz.
On Thursday 04 July 2002 00:02, teknokrat wrote:
> In my database i have values recorded in one minute intervals. I would
> like a query that can get me results for other time intervals. For
> example - return maximum value in each 3 minute interval. Any ideas
> how i can do this with sql? I tried writing a procedure in plsql but i
> am told it does not support tuples as output. I can get the all the
> one minute intervals and process them to get me three minute intervals
> in my application but i would rather not do the expensive call for the
> one minute intervals in the first place due to the large number of
> data. any ideas?
>
> thanks
>
>
>
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