Wednesday, January 15, 2014

New: Paper #4 Published

v.1 (January 2014)

Note: This paper assumes familiarity with the concepts and terminology introduced in papers #1, Business Modeling For Database Design and #2, The Costly Illusion: Normalization, Integrity and Performance, in this series, which are both recommended as preamble. 

If entities in the real world did not have identifiers—attributes that capture their identity and uniquely identify them—we would not be able to tell them apart. It follows that an accurate database representation of a business reality must include keys, R-table columns that formally represent the real world identifiers in the database.

Keys and kinds thereof, their necessity, selection, function and properties are too often not well known and understood. This paper
  • Defines and explains the key concept;
  • Explains the function and properties of the various types of key;
  • Describes the criteria for key selection;
  • Specifies what is proper DBMS key support;
  • Assesses SQL's key support;
  • Debunks some common misconceptions about keys.

Table of Contents

1. R-tables and Integrity Constraints
2. Keys and Key Constraints
3. Kinds of Keys
3.1. Natural Keys
3.1.1. Candidate and Primary Keys
3.1.2. Simple and Composite Keys
3.2. Surrogate Keys
4. Key Functions
4.1. Duplicate prevention
4.2. Integrity Burden Reduction
4. 3. View Updatability
5. Foreign Keys and Referential Constraints
6. DBMS Key Support
7. Keys in SQL
7.1. SQL and Duplicates
Appendix A: Duplicate removal in SQL
Appendix B: Duplicates and Language Redundancy

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