The concept of NULL – as value for “Empty”, or “Missing” – is violated for e.g. VARCHAR2 as the empty string ” is equivalent to NULL.

The open source world is full of people who would rather be right than rich.

–Tim

1) As to the question of Codd’s Rules as a test, according to Pascal in Aug of 2005, “I would not pay too much attention to Codd’s rules at this point, they have been deprecated. Codd formulated them as a quick and dirty way to counter all the nonsense that was floating at that early time, they are not orthogonal or systematic, and our understanding of RM has progressed considerably since then.” I would say that Chris Date, Hugh Darwen, or Fabian Pascal would probably be the best authority on what constitutes the current snapshot of what we might refer to as the “Relational Data Model Body Of Knowledge”. Having been a working practitioner at the time, I recall Codd’s initial Rules being in response to several ‘bandwagon’ attempts to claim that a DBMS was “Relational” just by slapping a “New & Improved”, “Now Relational!” sticker on it. Surveying the publications of the ACM SIGMOD group are not much help either, many of these academicians are working in ontologies and other XML-based semantic definitions of representing information, and not concerned per-se with the question of “What makes an RDBMS Relational?”

2) Issues about SQL to Oracle orthagonality – Any advanced SQL practitioner or DBA will most likely agree with the statement that “SQL has some serious inherent flaws”, part of being a skilled practitioner is knowing how to work around them. Creating non-relational “hacks” and “workarounds” like RowID and RowNum are not helping to counter the argument that SQL is not the be-all utopian Relational Data Management tool. But why MUST it be so? Certainly borrowing from other analogues, a mechanic employs a range of tools and trys to match the correct tool to the problem rather than attempting to use one for everything.

3) Regarding the ‘Oracle is an SQL DBMS not an RDBMS’ argument – Turning to the claimed “over-coupling” of Oracle’s Flagship RDBMS product line to SQL, this is a bit difficult to argue against, because in fact the critics are right. Here’s the fallacy, there is no need to tie such a fine product line to a rock [SQL problems], marrying it so unconditionally to SQL, and then have to constantly contend with the flaws and awkwardness of SQL through non-standard extensions, which produce a chorus of catcalls from the purists arguing to simply fix the standard. Certainly there is nothing stopping the Oracle product line from supporting ADDITIONAL (especially Non-SQL) native APIs, such as a direct link to a relational algebra notation.

Or here’s a completely outrageous idea on the face of it, Why not start a project to implement “D” as an API, the “much-heralded order of magnitude” improvement in technology over SQL. Date and his associates might be engaged to consult on constructing such an extension, and this could serve as a put-up-or-shut-up proposition.

In summary: Arguing whether Oracle is an RDBMS or simply an SQL-DBMS is perhaps more a matter more of perception than of reality, and any such negative perceptions are entirely within Oracle’s ability to resolve, should they desire it. “We have met the enemy, and he is us.” – Pogo