Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!boulder!bouguett
From: bouguett@boulder.Colorado.EDU (Athman Bouguettaya)
Newsgroups: comp.databases
Subject: Re: relational vs object-oriented
Message-ID: <6654@boulder.Colorado.EDU>
Date: 15 Feb 89 18:54:31 GMT
References: <376@uncmed.med.unc.edu> <152@bms-at.UUCP>
Sender: news@boulder.Colorado.EDU
Reply-To: bouguett@boulder.Colorado.EDU (Athman Bouguettaya)
Organization: University of Colorado, Boulder
Lines: 46

In article <152@bms-at.UUCP> stuart@bms-at.UUCP (Stuart Gathman) writes:
>
>An O-O database is a relational database whose field/attribute/column
>types are O-O "classes".  Therefore, the fields/elements/members are
>"objects".  The relation is called a "set" and the records/tuples/rows
>are called "records".  An aggregate class supports inserting records
>into and querying the sets.  (Just like an "array" aggregate class
>supports collections of objects in array form.)
>-- 
>Stuart D. Gathman	<stuart@bms-at.uucp>
>			<..!{vrdxhq|daitc}!bms-at!stuart>

I do not think that you are giving a proper definition of the
Relational and OO databases.  These two concepts are very different
from one another.  I believe that a more accurate definition would be
as follows:

The basic concept used in relational databases is the relation.  A
relation has attributes.  No behavior is embedded within a relation.
This latter is embedded within aplication programs.

The basic concept in OO databases is the object.  An object consists
of instance variables and methods.  The instance variables determine
the structure of the object whereas the methods define the behavior of
the object.  In class-oriented systems, similar objects are grouped
into a class.  Roughly speaking, if one makes a comparison with
programming languages, objects are equivalent to variables and classes
are equivalent to types with the exception that classes are used to
store some shared and default information whereas types are merely a
representation.  The other major component od OO databases is the
relationship.  Classes are related by relationships.  Their semantics
is as rich as one wants.  A priori, there is no limitation on the
semantics attached to relationships.

-Athman


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|                                                                 |
|Athman Bouguettaya   						  |	
|Dept of Computer Science, University of Colorado at Boulder.	  |
|E-mail: arpanet : bouguett@boulder.colorado.edu                  |
|	 csnet   : bouguett@boulder.csnet			  |
|	 bitnet  : bouguett@boulder.bitnet			  |
|        uucp    : {ncar|nbires}!boulder!bouguett		  |	
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