Newbie needs help creating folder with different date buckets

Question

A simplification my scenario, I have a table, Invoice, which contains invoice amounts and invoice dates. I want to break up the invoices amounts into date buckets, such that my target report should look something like this:
Invoices<30 Invoices<60 Invoices<90 Invoices>90
$100 $250 $500 $1000
I have created a folder from the Invoice table, and would like to know if it is possible to create new items within this folder to allow me to sum invoice amounts over the 0-30, 30-60, 60-90, 90+ invoice date ranges. In other words, can I create new items that each have their own condition?
I have seen other solutions that use a custom folder backed by a SQL query using case statements to break a table down into its date range buckets. Is this considered the "right" approach to the problem?
A simpler solution I've thought of is creating a folder for each date range (Invoices30, Invoices60, etc), and setting the condition of the folder to do the date filtering. The item "Invoice Amount" in each folder ends up being the bucket I want, and I would put them together in a complex folder, and build the report off the complex folder. Although inelegant and a bit redundant, would this solution work?
Thanks everybody!

Answer 1

Hi Newbie
You can do this right inside Discoverer using a couple of calculations.
Calc 1:
=====
Calculate the invoice date variance, let's say you will use TRUNC(SYSDATE) - TRUNC(INVOICE DATE). This gives you a number and let's call this new calculation VARIANCE.
Calc 2:
=====
This second calculation created the buckets themself. Let's do it using a CASE statement and we'll call the calculation TIME BUCKET.
CASE
WHEN VARIANCE <= 30 THEN "0 to 30"
WHEN VARIANCE <= 60 THEN "30 to 60"
WHEN VARIANCE <= 90 THEN "60 to 90"
ELSE "More than 90"
END
You now display only TIME BUCKET in your workbook. The other calculation, VARIANCE, will be used but not displayed on screen in the final answer.
If you don't like CASE, here's the same answer using DECODE:
DECODE(VARIANCE,
LEAST(VARIANCE,30), "0 to 30",
LEAST(VARIANCE,60), "30 to 60",
LEAST(VARIANCE,90), "60 to 90","More than 90")
By the way, when you do this you will find that Discoverer runs your report very fast. This is because it can handle these types of queries exceptionally well.
I hope this helps
Regards
Michael