Roll-Up/Drill-Down Problem with Discoverer

Question

Hi,
I am trying to produce some summary data, but am not exactly sure how to proceed.
Specifically, I have a table containing attendance data for a number of weeks. Part of table is shown below. 1 indicates attendance and 0 indicates absense.
|-------------------------------------------------|
| Attendance ID | Wk_1 | Wk_2 | Wk_3 | Wk_4 | ... |
|-------------------------------------------|-----|
| 0001 | 1 | 0 | 1 | 1 | ... |
| 0002 | 1 | 0 | 0 | 0 | ... |
|-------------------------------------------------|
Each student has a number of attendance_ids, each one represents a particular subject they study.
For example:
|------------------------------------------------|
| Student Name | Attend ID | Subject | Attendance|
|------------------------------------------------|
| Amberley | 0001 | IS3004 | 50 |
| | 0002 | MM3003 | 75 |
| | 0003 | PR3003 | 60 |
|------------------------------------------------|
In Discoverer, to create a percentage attendance, I add up all the columns and then divide by the number of weeks.
However, what I would really like to do, is to be able to roll this data up for summary based work and then to be able to drill down as necessary.
Looking at the Video Store Tutorial, Stores were rolled up into Cities and Regionsc, can anyone give me some pointers on how I could roll up my data?
Thanks,
Eddie

Answer 1

Hi Eddie,
Try looking up hierarchies in the Administrator Guide.
However, I'm afraid you'll have to pivot your attendance table in order to create a hierarchy.
Example:
Now:
att_id week_1 week_2 week_3 ...
1001 0 1 1 1
1002 1 1 0 1
1003 1 1 1 0
Needed for hierarchy:
att_id week_nr att_boolean
1001 1 0
1001 2 1
1001 3 1
1002 1 1
Look up "pivoting scenarios" in the data warehousing guide (OTN documentation) on how to do this (preferably a view on the original table, if necessary materialized view).
Then add additional time columns (or, better yet, create a time hierarchy table) with appropriate date hierarchy values, ie quarter and year. A weekbased hierarchy is tricky though, because weeks can "break" from one month/quarter/year to the other. So, figure this out carefully before you start creating you're time hierarchy.
Regards,
Sabine