Hi all,
I've got a table structured as follow and it's often filled with with new data each minute. Is it possible with a single query to retrieve data aggregation groupped by 15 minutes and half an hour ?? I can use GROUP BY SUBSTR(date,1,13) to get hourly aggregation but I really don't know how to get it with a lesser time.

Table structure
CREATE TABLE `test` (
`date` datetime NOT NULL ,
`value` float NOT NULL
) TYPE=MyISAM;

Sample data
+---------------------+------+
| date | value |
+---------------------+------+
| 2004-11-01 00:01:00 | 2 |
| 2004-11-01 00:02:00 | 1 |
| 2004-11-01 00:03:00 | 6 |
.......
| 2004-11-01 00:13:00 | 5 |
| 2004-11-01 00:14:00 | 7 |
| 2004-11-01 00:15:00 | 7 |
| 2004-11-01 00:16:00 | 6 |
......
| 2004-11-01 00:30:00 | 4 |
| 2004-11-01 00:31:00 | 3 |
| 2004-11-01 00:32:00 | 3 |
+---------------------+------+

desired result
| 2004-11-01 00:15:00 | 89|
| 2004-11-01 00:30:00 | 76|
| 2004-11-01 00:45:00 | 67|
| 2004-11-01 01:00:00 | 27|

Thank you very much!
Paolo Saudin

select from_unixtime(900*floor((unix_timestamp(`date`)+89 9)/900)) as quarterhour
, sum(`value`) as sumvalue
from `test`
group by quarterhour

Thank you very much !
Regard,
Paolo Saudin