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Lesson 4Introduction to business rules
ObjectiveDefine what Business Rules are and why they are necessary

Why are Business Rules needed in Database Design

Business rules are needed in database design to ensure that the data stored in the database adheres to the specific constraints and requirements of the organization or business. These rules can include constraints on the types of data that can be stored in a particular field, the format of data, and the relationships between different tables in the database. By including these rules in the design of the database, it can help to ensure that the data stored is accurate, consistent, and useful for making business decisions. Additionally, it can also help to prevent data entry errors, and improve the overall efficiency of the database system. A business rule is a condition that reflects a specific business need, which the software must accommodate. The ability to accommodate business rules is critical to any software product’s effectiveness.

Enforcing Business Rules

Business rules are enforced within MS SQL Server 2012 in a variety of ways:
  1. Primary keys
  2. Foreign keys
  3. Rules
  4. Defaults
  5. Triggers
  6. Stored procedures
  7. Constraints

Azure SQL

Importance of business rules

Business rules can be quite complex, which is why there is no single way to enforce them. It is imperative that you understand and document the rules that govern how a company does business. This ensures that there are no “holes” in the system that bypass a business rule. Business rules also enforce data integrity. For example, suppose the business has a rule that states the following:
No employee shall have a salary of $100,000/yr or greater if they are at or below a paygrade of L-3.”
This business rule can be enforced by a variety of means, such as a Trigger, Stored procedure, or constraint. However, there are potential implications of using each of these database objects.
All of the types of database objects listed above are discussed throughout this course and the other courses in this series. This introduction serves as the “jumping off point” for getting you to think in terms of business rules.
In the next lesson, we will cover primary keys and unique constraints.