Re: Network databases

"Alfredo Novoa" <alfredo_novoa_at_hotmail.com> wrote in message news:238ju0te9m1fkaquc04enq7ld575e91q4p_at_4ax.com...
> On 14 Jan 2005 14:25:08 -0800, lynn_at_garlic.com wrote:
>
>>Alfredo Novoa wrote:
<snip>
A second school of thought argues that if a database does not
> implement all of Codd's rules, it is not relational. This view, shared
> by many theorists and other strict adherents to Codd's principles,
> would disqualify many database systems from being considered "truly
> relational". In fact, any database that uses the Structured Query
> Language (SQL) to access and modify data is not an RDBMS under this
> definition. Advocates of this philosophy refer to systems that follow
> some but not all of the rules as Pseudo-Relational Database Management
> Systems (PRDBMS). For clarification, they often refer to DBMSs that do
> follow all of the rules Truly-Relational Database Management Systems
> (TRDBMS).
>
> </quote>
>
> I am a member of the second school :)
>
> But it is not very correct. Codd's rules are outdated since a long
> time ago.

So, the relational model is one where parts of it can become outdated? ;-) Is it more accurate to say that some of Codd's rules have been shown to be unnecessary, incomplete, or incorrect, rather than "outdated"?

> We can find a modern interpretation of the Relational Model
> in "The Third Manifesto".

And what criteria could we use to show that "The Third Manifesto" does not also have parts that have become outdated? In fact, Date has made modifications since that time, particularly related to temporal databases and maybe even related to non-1NF (I forget precisely what is in TTM compared to the 8th Edition of Intro to Databases).

If a database management system stores & retrieves data in a way that is logically based on mathematical relations (as defined and largely agreed upon by the mathematical community rather than one of the many odd definitions given by some one person working with databases) and includes operations on those relations, then it seems to me that it may claim to be an RDBMS.

Of course, soon enough companies will be clamouring to call their DB's something other than (just) relational, I suspect.

Cheers! --dawn Received on Sun Jan 16 2005 - 04:42:16 CET