What is a Business Rule, its purpose in Data Modelling?

When database designers selecting / determining the entities, Attributes, relationships etc. That are used to build a Data model with a thorough understands., viz.

    1.      What types of data are used in an organization.

    2.      How the data are used.

    3.      What reports that they need after processing?

From the database point of view, the collection of data becomes meaningful only when it reflects properly defined business rules.

Thus, a business rule is a brief, precise and unambiguous description of a Policy, Procedure, or Principle within a specific organization.

Business rules, thus, derived from a detailed description of an Organization’s operations, that help to create and enforce actions within that organization’s environment.

To be effective, Business rules must be in written, properly defined, easy to understand to every person in the Organization., shares a common interpretation of the rules.

Some of the Example of Business rules are,

 i)   A customer may generate many invoices

ii)   An invoice is generated by only one customer

iii) A training session cannot be scheduled for fewer than 10 employees or for more than 30 employees., etc.

Purpose of Business Rules:

The business rules are essential to Database designer for several reasons, such as

     a)       They help standardize the Company's view of data

     b)      They can be a communication tool in between users and designers

     c)      They allow the designer to understand the nature, role and scope of Data

     d)      They allow the designer to understand business processes

    e)      They allow the DB designer to understand to develop appropriate relationship participation rules and constraints to create an accurate data model....so on.