Need help with sum from previous years

Question

Hi All,
In a report i have 4 fields. The first field shows the YTD invoice totals for the current FY 2010 (which i accomplished). The other 3 fields are :
2nd field Sum of the value of invoices for the FY 1YEAR prior to the current year
3rd field Sum of the value of invoices for the FY 2YEAR's prior to the current year.
4th field Sum of the value of invoices for the FY 3YEAR's prior to the current year.
How can i get the desired results for the second,third and the fourth fields, please need help or advice.
Thanks

Answer 1

Hi
If you have the values for several years in the same report you should be able to do what you want using the analytic LEAD and LAG.
LAG will retrieve values from previous rows whereas LEAD will retrieve values from following rows.
The basic syntax is the same and look like this:
LAG(value, offset) OVER ({optional_partition_clause} ORDER BY mandatory_order_clause)
The ORDER BY clause is mandatory and cannot be omitted. However, this ORDER BY has nothing to do with the sort order you manually create in the worksheet. Generally, most people will set their sort order the same as the ORDER BY in the calculation.
Here's an example that gets year to date from 2 financial years ago:
LAG(YTD,2) OVER (ORDER BY FY)
You have to understand that Discoverer will pull values from previous rows not from previous cells as displayed on the report, although if the cells may happen to be rows too then it will appear as though it is pulling previous cells. I personally am very experienced with analytuc functions and can make manipulate data within Discoverer just about any way that I want. Generally, if I can see data on the screen even when they are in different cells or rows I can create functions to manipulate it. This capability only comes about as a result of experience and I would strongly advise you to practice with the analytics and see if you can at least master some of them. You'll find your Discoverer capabilities will improve dramatically and you will become a great asset at work.
When working with a new report I generally duplicate the report as a table so that I can see the values. Then if I need to sort the items in order to line up the values I want to work with I do so. Having worked out what sort order I need I can then see what offset I use then I create the analytic and use it in the main worksheet.
Hope this helps
Best wishes
Michael