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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.