Re: oodb <-> rdb

In article <BwsoA4.LHz_at_brunel.ac.uk> Dulan.Weerasinha_at_brunel.ac.uk (Dulan Weerasinha) writes:
>
>Hi Folks,
>
>I am in the process of looking into the possibility of translating
>Object-Oriented concepts to Relational concepts.
>

Hmm. Looks like you're going in the wrong direction :-). It's much easier implement Rdb concepts in OO, since a TABLE is an object. :-)

>I would be grateful if somebody could provide me with pointers on the following:
>
>Given an object, what needs to be considered/done for an object to be
>translated to a relation (or a set of relations). Similarly, given a relation
>(or a set of relations), what do you need to consider when re-creating the
>corresponding object.
>
>What issues need to be considered during the translation process?

The very simplistic mapping is:

       class  <=> table
       object <=> row
                                   

>
>How, if at all possible, is object behaviour captured in the rel. model?
>

In a relational model there is no behavior, only data. Some extended RDB systems (eg. Sybase) allow you to store code in the database - but the code is usually not connected with any particular table.

>What rules do you have to follow or what heuristics do you have to apply?
>

There are two articles you might find interesting, they both appeared in CACM:

   W. J. Premerlani, et al. "An Object Oriented Relational Database",

       CACM, Nov 1990

   C. Kung, "Object Subclass Hierarchy in SQL: A Simple Approach",

       CACM, July 1990.

Hope this helps.

...richie

-- 
* Richie Bielak   (212)-815-3072   |                                          *
* Internet:       richieb_at_bony.com | Rule #1: Don't sweat the small stuff.    *
* Bang {uupsi,uunet}!bony1!richieb | Rule #2: It's all small stuff.           *
*    - Strictly my opinions -      |                                          *