Note: To demonstrate the soundness and stability conferred by a sound theoretical foundation (relative to the industry's fad-driven "cookbook" practices), I am re-publishing as "Oldies But Goodies" material from the old (2000-06) DBDebunk.com, so that you can judge for yourself how well my arguments hold up and whether the industry has progressed beyond the misconceptions those arguments were intended to dispel. In re-publishing I may revise, break into or merge parts and/or add comments and/or references that I enclose in square brackets). 

One of the core objectives of this site (and my work) has been to demonstrate that there will not be progress in data management as long as the industry and trade media require and promote exclusively (mainly tool) experience in the absence of foundation knowledge. I have published and analyzed ample evidence that relational language and terminology are used without grasping what it actually means -- a good way to gauge lack of foundation knowledge.

Recently I posted a four part series titled "Nobody Understands the Relational Model" showing that even a practitioner steeped in the RDM does not really understand it. Consider now a practitioner's mistake at the beginning of career -- "a bad database schema and what it did to system performance" -- which, he claims, belatedly taught him a lesson. Hhhhmmm, did it, really?

Note: To demonstrate the correctness and stability offered by a sound theoretical foundation (relative to the industry's fad-driven "cookbook" practices), I am re-publishing as "Oldies But Goodies" material from the old (2000-06) DBDebunk.com, so that you can judge for yourself how well my arguments hold up and whether the industry has progressed beyond the misconceptions those arguments were intended to dispel. I may revise, break into parts, and/or add comments and/or references, which I enclose in square brackets).

“Many of us ... do not think that harmony is the great goal, or unity or peacefulness, [and] actually quite like hard questions for their own sake, and enjoy ... the life of the mind. To the question of how to live, the answer is "by disagreement.” --Christopher Hitchens

Let me say, first and foremost, that as the subtitle of the book -- A REFERENCE FOR THE THINKING PRACTITIONER -- indicates, it is targeted at the minority of practitioners who think clearly, independently and critically. It should not be a surprise, then, that those not belonging to that (alas, very small) target audience don't see its practical value. As I said so many times, if my work gained mass appeal, I would wonder what I was doing wrong. This is the sad reality, whether we like it or not. In fact, to be consistent I will go one step further: I don't assume that positive reviews are any better than negative ones -- they are frequently grounded in as faulty reasoning and/or ignorance as the critiques.

Let me also make clear that I do not place all of the blame on  the individual database practitioners or users. Rather, problems are rooted in a systemic, much more profound societal and business culture that fails to instill and encourage foundation knowledge and independent, critical thinking, which not only does not reward, but actually punishes such. This is true to a degree in all societies, of course, but in the US the problem is much more acute (there can hardly be a better demonstration of the horrendous implications of this than how the election was covered, perceived and accepted by most of the press and public) [I wrote this prior to the last two elections -- I leave it to the reader to judge the steepness of the subsequent regress.]

with David McGoveran

(Title inspired by Richard Feynman)

In Parts 1 and Part 2 we provided some clarifications following a discussion on LinkedIn about our contention that, conventional wisdom notwithstanding, database relations -- distinct from mathematical relations -- are by definition not just in 1NF, but also in 5NF, as a consequence of which the RA, as currently defined for 1NF closure, produces what the industry calls "update anomalies" and, thus, is not a proper algebra. In Part 3 we used that information to debunk some leftover misunderstandings in the discussion.

We conclude in Part 4 with comments on a private exchange that followed the public one on LinkedIn regarding the difference between the McGoveran (DMG) and Date and Darwen's (TTM)
interpretations of the RDM, which can be summarized as follows:

Note: Each "Test Your Foundation Knowledge" post presents one or more misconceptions about data fundamentals. To test your knowledge, first try to detect them, then proceed to read our debunking, reflecting the current understanding of the RDM, distinct from whatever has passed for it in the industry to date. If there isn't a match, you can review references -- reflecting the current understanding of the RDM, distinct from whatever has passed for it in the industry to date -- which explain and correct the misconceptions. You can acquire further knowledge by checking out our POSTS, BOOKS, PAPERS, LINKS (or, better, organize one of our on-site SEMINARS, which can be customized to specific needs).

“The key idea is "Parent-Child" relationship. Entities ~ Relations ~ Tables (tilde stands for "more or less like"). Concept of a Table resonates with most of the people just as everybody intuitively grasps a concept of "rows and columns” but might struggle with "tuples and attributes". Explain relations and relationships, 1:1, 1:N, N:N etc. Explain rationale for this way of collecting and storing data, touch upon data normalization, and tell a few anecdotes about cost of storage back in 1970 and Y2K problem it have caused; add that we have inadvertently created Y10K problem while fixing it (not exactly true but not wrong either). Show an ERD diagram, trace the relationships, introduce SQL, maybe run a few simple SELECT queries to help your listeners visualize it, including equijoin and ORDER BY. Save other JOIN types, data types and other, more advanced topics, and for the next encounter.”

--Quora.com

 An excellent example that validates my claim of lack of foundation knowledge in the industry: most "explainers" of RDM have acquired relational jargon, but do not know or understand it at all.

(Title inspired by Richard Feynman)

In Parts 1 and 2 we provided some clarifications following a discussion on LinkedIn about our contention that, conventional wisdom notwithstanding, database relations -- distinct from mathematical relations -- are by definition not just in 1NF, but also in 5NF, as a consequence of which the relational algebra (RA), as currently defined for 1NF closure, produces update anomalies and, thus, is not a proper algebra. In this third part we will use that information to debunk some leftover misunderstandings in the discussion.