Business Data Diagram (BDD) defines the structure of how data is thought of in a business. BDDs are an RML data model which show the relationships between business data objects. They show how many of one object can be related to another object (which is a cardinality), such as how many shipped products or payment types an order can have. BDDs look similar to Entity Relationship Diagrams (ERDs), but BDDs are actually conceptual data models that show business data objects from a business user perspective, while ERDs show the implementation of data objects in a schema.

Any project that has databases will use BDDs, which means that most projects will need them. Creating a BDD for every object in your solution may not be necessary. Focus on the major business data objects the business cares about. From there, your BDD will allow you to figure out what is missing from a system based on the relationships between entities.

For more information on Business Data Diagrams, visit Data Migration Part 1 – Know Your Data.

Learn more about requirements models in our book Visual Models for Software Requirements (Microsoft Press, 2012) Joy Beatty and Anthony Chen. (See Chapter 19 for Business Data Diagrams)