Section 0: Module Objectives or Competencies
| Course Objective or Competency |
|---|
| The student will be able to recognize business rules and their impact on the design of a database. |
Section 1: Business Rules
To develop an accurate data model, the designer must have a thorough understanding of the company's data types and their extent and uses.
However, data do not, by themselves, yield the required understanding of the total business.
From a database point of view, the collection of data becomes meaningful only when business rules are defined.
Business Rules
- Business rules are a brief, precise, and unambiguous description of a policy, procedure, or principle within a specific organization's environment.
- They apply to any organization that stores and uses data to generate information.
- They provide a description of operations that help to create and enforce actions within that organization's environment.
- Business rules are sometimes external to the organization (FERPA, IRS).
Example
- A customer may make many payments on an account.
- Each payment on an account can be credited to only one customer.
- A customer may generate many invoices.
- Each invoice is generated by only one customer.
- If the amount of the invoice is over $1,000, it cannot be paid until authorization is received from management, so the invoice appears on the cash requirements report. If the amount is less than $100, payment is authorized immediately, since it is costly to delay payment, only to process the invoice again in a few days. If the invoice amount is between $100 and $1,000, inclusive, payment is authorized unless it is 10 days old or less and there is no early payment discount. For the latter cases, payment is delayed since it will tie up capital without giving a return. Such invoices are set aside until the next time authorization is checked.
Sources of Business Rules
- Policy makers (company managers, department managers, etc.)
- Written documentation (like operations manuals, standards, etc.)
- Direct interviews with end users
Importance of Business Rules
- Knowledge of business rules is essential for the creation of an accurate data model.
- They allow designers to understand the nature, role, and scope of data.
- They force designers to understand business processes.
- They make it possible for designers to develop appropriate relationship participation rules and constraints.