Data Modeling - Business Rules

A business rule is a statement that defines or constrains some aspect of the business.

According to the white paper by the Business Rules Group, a business rule falls in this category:

• Definitions of business terms (Entity)

The most basic element of a business rule is the language used to express it. The very definition of a term is itself a business rule that describes how people think and talk about things. Thus, defining a term is establishing a category of business rule. Terms have traditionally been documented in a Glossary or as entities

• Facts relating terms to each other (relationships and cardinality),

E.g. a customer can place one or many order is a business rule. Facts can be documented as natural language sentences or as relationships, cardinality, attributes

• Constraints (also called “action assertions”)

Every enterprise constrains behaviour in some way, and this is closely related to constraints on what data may or may not be updated. To prevent a record from being made is, in many cases, to prevent an action from taking place.

• Derivations (calculated or deduced)

The business rules can be completely represented in a logical data model

A business rule is known in the data quality field as a data rule.

In the datawarehouse (ETL/ELT) field, the business rules are applied on the data through transformation rules such as expression, filter, pivot..

Example of a business rule for an application that will register submitted papers:

• Each Committee ChairedBy at most one Person
• Each Person who chairs a Committee must also IsMemberOf that Committee
• Each Reviewer Reviews at least one Paper
• Each Paper which is WrittenBy a Person must not ReviewedBy with that Person