I am working on entirely new papers (not re-writes) in the PRACTICAL DATABASE FOUNDATIONS series. I have already published two:

• THE FIRST NORMAL FORM - A DEFINITIVE GUIDE
• PRIMARY KEYS - A NEW UNDERSTANDING

available for ordering from the PAPERS page, and two more:

• RELATIONAL DATABASE DOMAINS: A DEFINITIVE GUIDE
• DATABASE RELATIONS: A DEFINITIVE GUIDE

are in progress and forthcoming, respectively.

In the process I am coming across industry common and entrenched "pearls" that I am using for my "Setting Matters Straight" (SMS) and "To Laugh or Cry" (TLC) posts on Linkedin. I do those posts to enable the few thinking database professionals left realize how scarce foundation knowledge is, and to illustrate fallacies that abound in the industry, of which they are unaware, and which the papers are intended to dispel.

Time permitting, I may expose and dispel some of those fallacies (treated in more depth in the papers) in short posts here, such that those thinking professionals can test their knowledge and decide whether the papers are a worthy educational investment.

Here comes the first--a TLC I posted on LinkedIn.

“The company was using a [SQL] RDBMS . . . to handle data transactions for its trading applications. However, the applications required arbitrary data types, which is nearly impossible for relational systems, according to experts.”

 which contains three fallacies--can you identify them before you proceed?

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•  "SQL RDBMS" is a contradiction in terms. Not only are SQL DBMSs not relational (and, thus, fail to provide RDM's advantages), but--even leaving SQL out--the interpretation (and, thus, understanding, such as it is) of RDM dominant in the industry is flawed. Do you know why, and what are the missed advantages?

• "Arbitrary data types"--more precisely, domains of arbitrary complexity (not to be confused with SQL built-in types)--are not impossible in RDM properly understood, namely, as coupled with a strong type system: a notion of type hierarchy derived from a theory of types that governs manipulation of domain values, which is orthogonal to RDM, albeit necessary, for support of domains in general, and those so-called "complex" in particular (orthogonal in the sense that the relational data sublanguage is insulated from the implementation of the domains and their operators). Such a type system is incorporated in McGoveran's Semantic-Relational Data Model (SRDM)--the correct interpretation, extension and formalization of Codd's work.

• As to "experts", I do not know many (to understate the case) in RDM and I assure you that the above statement was not made by any of them.

References

McGoveran, D., LOGIC FOR SERIOUS DATABASE FOLK (draft chapters), forthcoming.
Pascal, F., RELATIONAL DATABASE DOMAINS, forthcoming.

In Part 1 we introduced in the conceptual model (CM) the metalogical designation property. It represents—in the absence of known shared defining properties of an entity type, the designation by a group's definer that an entity identifier (aka assigned name) or property value is a member of the group. Such a group is not a group of entities, but a group of name and property values. In the logical model (LM), it is formalized as a designation predicate (DP) and defines a domain.

In Part 2, we introduce the metalogical assertion property. It represents the assertion by an authorized database user that a specific entity, represented by a tuple, either does or does not correspond to an actual entity in the real world.

 with David McGovern

One purpose of our contributions here is to suggest a vocabulary that avoids confusion not just within the formal logical level, but also between conceptual and logical terminologies, which is widespread in the industry and is exacerbated by limitations of natural language (NL). We use the following terminology in our approach to conceptual modeling:

• Objects are:

- Primitive (basic entities);

- Compound:

  - groups of related entities;

  - multigroups (groups of related groups);

• Properties are:

- Individual (of basic entities);

- Collective:

  - Of groups: relationships among entities within a group;

  - Of multigroups: relationships among groups within a multigroup.

Note:  It is a McGoveran insight that relationships between objects at a lower aggregate level are properties of the object at the higher aggregate level which the former comprise (LOGIC FOR SERIOUS DATABASE FOLK, forthcoming; see draft chapters) http://www.alternativetech.com/ATpubs_dir.html For classification of properties as first, second, third and fourth order (1OP, 2OP, 3OP and 4OP) see RELATIONSHIPS AND THE RDM Parts 1-3. https://www.dbdebunk.com/2023/03/relationships-and-rdm-v2-part-1.html All such properties can be expressed logically in a FOPL-based relational data sublanguage as constraints, which is beyond the scope of this discussion.

Due to: 

1. Taking care of some health issues that have accumulated (not getting any younger);

2. Concentration on the Israel-Hamas War;

3. Effort to update old papers and write new ones;

4. Much needed rest and the holidays.

I am taking the remaining of the year off and will re-start my contributions in January.

Wishing you and yours season's greetings and happy holidays!

After 23+ years DBDebunk.com has undergone a slight refresh. Here is an outline of the changes.

1. The BOOKS and PAPERS are now unified into one PUBS page from which my papers and self-published books can be ordered. There are two paper series:

• Understanding the Real RDM: reviews and analysis of some Codd's published papers 1969-85 in the spirit of McGoveran re-interpretation of his work--distinct from that dominant in the industry.
• Practical Database Foundations: shorter papers about narrower aspects of the RDM that are abused, misused and ignored in the industry.

Some papers will be brought up to date/re-written and new ones will be published.

2. The recommended books links from the BOOKS page have been moved to the LINKS page.

3. The FUNDAMENTALS page was replaced by a SEARCH page that contains a newly compiled data and relational fundamentals comprehensive dictionary of terms to be maintained on a regular basis. It includes abbreviations/acronyms to be used as labels for searching. Use the page as a reference in conjunction with the labels to compensate partially for a limitation of the Blogger labels facility.

4. Labels now exist only for the search terms that have known abbreviations  or acronyms. The SEARCH page should be used to identify which terms have labels and those that do not must be used with the Blogger search facility (see details on ABOUT page).

Any problems, comments, suggestions, questions, or support are welcome--drop me an email.

Note: This a revision of an earlier post

RDM is an application to database management of mathematical relation theory (MRT) consistent with simple set theory (SST) expressible in first order predicate logic (SST/FOPL) that is used to formalize symbolically conceptual models of reality as logical models for database representation.

In RDM a domain can "appear" in multiple relations: the domain represents an abstract property, attributes defined on it represent that property in contexts of specific entity groups that relations represent. For example, attribute SALARY in relation EMPLOYEES represents the property represented by domain MONEY in the context of entities of type Employee and attribute BUDGET in relation DEPARTMENTS represents it in the context of entities of type Department.