Information Modeling and Relational Databases, 3rd Edition

4 Uniqueness Constraints

Abstract

This chapter discusses how to add uniqueness constraints (UCs) to an ORM conceptual schema. It covers internal UCs on unary, binary, and longer fact types as well as external UCs between fact types. It then shows how to check that the fact types are atomic.

Keywords

ORM; Uniqueness constraint; Conceptual join; Arity check; Projection; Join

Chapter Outline

• 4.1 Introduction to CSDP Step 4
• 4.2 Uniqueness Constraints on Unaries and Binaries
• 4.3 Uniqueness Constraints on Longer Fact Types
• 4.4 External Uniqueness Constraints
• 4.5 Arity Checks
• 4.6 Projections and Joins
• 4.7 Summary

4.1 Introduction to CSDP Step 4

So far, the conceptual schema design procedure (CSDP) has focused on specifying the elementary fact types, ...