Beginning Database Design Solutions, 2nd Edition

6Extracting Business Rules

Chapter 5, “Translating User Needs into Data Models,” explained how to build models to represent the entities involved in a database project and to study the interactions among those entities. The final kind of model described in that chapter, the relational model, has a structure that closely mimics the organization of a relational database. You can easily convert a relational model into a working relational database.

Before you do, however, you should optimize the relational model to make the final database as flexible, robust, and efficient as possible. Optimizing the model now is easier than reorganizing the database later, so it's worth taking some time to make sure you get the database design right the first time.

The first step in optimizing the database is extracting business rules. Keeping business rules separate from other database constraints and relations, at least logically, makes later changes to the database easier.

In this chapter, you will learn:

• Why business rules are important
• How to identify business rules
• How to modify a relational model to isolate business rules

After you understand business rules, you'll be able to use them to make your databases more flexible and easier to maintain.

WHAT ARE BUSINESS RULES?

Business rules describe the objects, relationships, and actions that a business finds important and worth writing down. They include rules and policies that define how a business operates and handles its day-to-day operations. ...