Dimension table to support Hierarchy and the aggregation functions

Question

Hello expert,
Now I seem to know why those aggregation functions e.g. SUM, COUNT failed whenever the report is executed.
I have a fact table REJECT_FACT contains all the information of rejects:
Reject ID
Reject Category
Reject Code
Reject Desc
Site Desc
Site Code
Region Desc
Age Group
Reject Date
So I created a alias REJECT_DIM based on REJECT_FACT. After several trials, I think that the aggregation functions do not work with alias because after I remove the REJECT_DIM, the aggregation seem working.
Is my concept right? Or I am missing something? I don't understand that the data model for datawarehouse should be simple, why do we need to create many dimension tables to support the hierarchy?

Answer 1

Hello expert,
Thank you very much for your reply.
Actually the data model is very simple. There is only one physical table REJECT_FACT. The structure is as follows:
Reject ID (NUMBER)
Reject Category (VARCHAR2)
Reject Code (VARCHAR2)
Reject Code Desc (VARCHAR2)
Site Desc (VARCHAR2)
Site Code (VARCHAR2)
Region Desc (VARCHAR2)
Age Group (VARCHAR2)
Reject Date (DATE)
The hierarchy required is as follows:
Reject Category -> Reject Code Desc -> Site Desc -> Region Desc -> Age Group -> Reject Date.
I want to produce count on each hierachy level.
How to populate the hierachy structure effectively?
Thanks......