• FT Relation Interpretation
  
• L/C Tree Prediction in SQL 
  
• L/C "Purpose built systems"
• SMS Primary Key Immutability
• FT Kinds of Surrogate Key
• SMS Imaginary Keys 
• FT Uniqueness Is Relationship
• SMS SST/FOPL & Keys

Note: 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.

In the process I am coming across industry common and entrenched "pearls" that I am using for my "What's Right/Wrong with this Database Picture, or "Setting Matters Straight" (SMS), and "To Laugh or Cry" (TLC) posts on Linkedin. I do these 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 specify those fallacies in brief posts that I set straight in the papers, 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 just 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?

 New, completely re-written. Available to order here

Table of Contents

Series Preface

Abstract

Introduction

1. Entities, Properties, Names, and Identification

2. Relational Representation

3. Relational Keys

    3.1. Kinds of Keys

           3.1.1. Candidate, Primary and Alternate Keys

           3.1.2. Natural and Surrogate Keys

4. Formal Primary Key Mandate

5. Primary Key Designation

6. Keys and Constraints

7. Keys and Performance

   7.1. Keys and Indexes

Conclusion

References

Appendix A: Keys in SQL

Appendix B: Duplicates and Consequences

B1. Duplicate Interpretation

B2. Duplicates in SQL

      B2.1. Duplicates and Correctness

      B2.2. Duplicates and Query Nestability

      B2.3. Language Redundancy & Duplicates

      B2.4. Duplicates and Performance Optimization

      B2.5. Duplicate Removal

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!