[news.eclipse.birt] Re: How to calculate difference between current and

[Tobias Mayer <eclipse-ng@xxxxxxxxxx>]

Hi Jason,

i'm using a Flat File Datasource not a scripted one, so i can't 
calculate it there. Or did i miss a thing?

I got it working using a calculated column inside the chart, only there 
i have access to the rownumber. But i would prefer a solution inside the 
original datasource.

Tobias

Jason Weathersby wrote:
> Tobias,
>
> To get the previous value you could create a computed column to do this.
>
> First in the dataset beforeOpen script add a JavaScript variable like this:
>
> prevVal = 0;
>
> Then add a computed column like this:
> var tPrevVal = prevVal;
> prevVal = row["thecolumniwantthepreviousvaluefrom"];
> tPrevVal;
>
> The only value that will really  not be valid is the first.
>
> Jason
>
>
>
> Tobias Mayer wrote:
> > Hi,
> >
> > ich have a CSV-File containing one column with Date values. Now i need 
> > to somehow create another column containing the difference of days 
> > between the current row and the previous one. I found out how i could 
> > calculate this difference, but i don't know how i can access the data 
> > of the previous row. Any suggestions/solution?
> >
> > TIA
> > Tobias Mayer