Question

I need your help in following case.

i have table ChartData

in that table i have large number of records as per below

PK,ProjectID,MAchineId,Powervalue,PowerData
1     1         1         20.5     2011-07-05 12:00:00    
2     1         1         21.5     2011-07-05 12:01:00
3     1         1         22.5     2011-07-05 12:02:00
4     1         1         23.5     2011-07-05 12:03:00
5     1         1         24.5     2011-07-05 12:04:00

6     1         1         25.5     2011-07-05 12:05:00    
7     1         1         26.5     2011-07-05 12:06:00
8     1         1         27.5     2011-07-05 12:07:00
9     1         1         26.5     2011-07-05 12:08:00
10     1        1         28.5     2011-07-05 12:09:00

Output

PK,ProjectID,MAchineId,Powervalue(Avg value of power),PowerData

1     1         1           20.5            2011-07-05 12:00:00    
6     1         1           25.5            2011-07-05 12:05:00    

any help would be appreciated. thanks in advance.

Answer 1

I guess you want to aggregate every five tuples? If so, maybe something like this will help:

SELECT PK, ProjectID, MachineID, AVG(Powervalue), PowerData FROM table GROUP BY (PK-1)/5

although I don’t really know if you can do that with GROUP BY

@gbn: I would like to answer to your comment directly, but I think I lack the privilege. Can you explain why this will fail on all but MySql?