How genralizationa and aggregation in ER Diagram to a physical RDBMS. Can any body have some example of such a scenario?

there are some good resources here --> generalization and aggregation in ER diagram

Thnks r937:

Here is my origional problem:

I am going to develope a Help DesK, The user will raise a ticket by selecting some predefind set of services like:

1. Software Maintinance
2. Office equipment Maintinance
3. Newtwork Problem etc etc

I have a table like the following:

ServcieId,
ParentServiceID,
ServcieName,
ServcieProvidingArea
etc etc

Now my problem is there are varying needs of each and every service category like:

If the user selected Networ services , he must mention whether the problme is in WAN, Lan or Ring0 Network. (We call this attribute as Network Type)

If the user select PHOTOCOPIER MAINTINANCE he/she will have to mention
COUNTER (a number that indicates the number of copies done by the photocopier till date )

now the problem i here is that we do the service Netowrk Problem has nothing to do with COUNTER and similarly the Service Photocopier maintinance has nothing to do with Networ Type.

This situation gives me the idea that I should user Generalization/Specialization etc.

1. Am I right in guessing that this is a problem to be solved using Generalization/Specialization?

2. If yes then how to apply Generalization/Aggregation to this problem , If No what is the physible solotuion to the problem

yes

see What to do when the same entiry has diffirent attributes

Is there some other elagent solution then the one given there? My study/Research shows that this is a problem of Specialization but I cant understand how to solve it with Specialization.

that ~is~ an elegant solution

the service type table is the generalization (supertype), and the various detailed service tables are the specializations (subtypes)