Conclusion An Entity Relationship Diagram is a great tool to help you define, understand, and communicate the requirements of a system. It can be modelled at a high level (conceptual data model), a detailed level (physical data model) or a level in between (logical data model).
If you’re looking for a way to define how data is set up in your business analysis system, you’re going to love the entity relationship diagram (ERD). The ERD helps you organize and document the various data entities and their relationships to one another within the project.
There are several types of relationships that are represented on an ERD: One to one: One record of an entity is directly related to another record of an entity One to many: One record of an entity is related to one or more records of another entity.