Date Track history tables in Oracle HRMS & Discoverer

Question

Hello experts,
I will be glad if anyone can help thru. I am trying to develop the DIS report for Audit purpose that tracks all the changes entered by Data Entry clerks, regardless of effective date. Mainly from Person Form and Assignment Form.
Is there anyway I can include the exact date/time the change made/status updated. Is the 'Effective date' clue?
e.g. There is an Assignment Change - from 'Global Operations' organization to 'Domestic Application' organization. The change is suppose to be effective from 05/02/2011 but I am entering the action on 04/18/2011. Similar for past events - if I make date tracked Assignment change suppose to be effective from 04/04/2011.
How can I accommodate this in a report. I just have EUL rights of Discoverer10g. (Oracle R12)
Thanks a lot.

Answer 1

Hello
The effective date is used for date tracking, but not to determine when a change was made. To determine when a change was made you need to look at the date last updated. Bear in mind though that only tables which can be updated have this field. If a table is only used for inserts then you will not find this field.
The effective dates are used to tie records in different tables together. Some tables have just an effective date, some have an effective start and an effective end, while others have a FROM date and a TO date. All of these can be used together to determine the state of play as it was at a certain point in time. The current records can have their effective dates compared to SYSDATE like this:
EFFECTIVE_START_DATE <= SYSDATE and EFFECTIVE_END_DATE >= SYSDATE
Records from one table can be tied to records in another to ensure for example that an assignment is tied correctly back to the right person record. In this case you would need to make sure that the effective date on the assignment is greater than or equal to the effective start date of the PERSON and less than or equal to the effective end date.
Date last updated will be used to determine exactly when a record was updated. Sometimes a date last updated will pre-date an effective date when companies enter records in advance of when they will be active. For example, in payroll where it is very common to enter new salaries many weeks in advance or in your situation where a change is supposed to be effective from 05/02/2011 but is entered on 04/18/2011. In this case the date last updated will say 04/18/2011 and the effective date or effective start date, depending which is in use, will have 05/02.2011. The effective date, effective start date and date from should never change and should always reflect a record's effectiveness, regardless of many times the record gets updated. The effective end and from dates will be updated to a real date a new record is added and sometimes these will be NULL so you have to take that into account too.
Data warehouses will generally load data based on the date last updated so that, for example, all records updated in the last 24 hours can be selected.
Hope this helps
Michael