Weekly, Monthly Averages?

[buls]

Hi, I am working with Jasper iReport Designer and want to ask how can I calculate an average sum of a column baced on a date? 

I am working on a report which has a database containing a table two columns: 1st is "sample_time" which has DATE values and the second is a "watt" which has an int value.

What I want to do is take the "watt" column and show it as average on the report (which I can do), and then show the same column "watt", but from averages based on the dates from the other "sample_time" column.

Lets say I have the dates from 2008-01-01 to 2008-01-20 and I want to do a weekly average, lets say from 01-01 to 01-07, how can I do that? 

 

Best regards,

Vinny

[sadakar]

Make use of varialbes for avg . In the variable expressions restirct your avg accroding to dates.

For eg:

In your variable expression ,    avg(watt) when date>='01-01-2014' and '01-07-2014' . If take these two values in parameters you can make the expression more generic. Hope this idea will helpful.