Solution 2: Entity Relationship Diagrams

Solution 2: Entity Relationship Diagrams

This is part of an ongoing blog series on onboarding to real-world data. See Q1 2023 Plinth Blog Series | Onboarding to RWD for an overview!

Entity relationship diagram

Example of an entity relationship diagram (ERD).
Example of an entity relationship diagram (ERD).

Real-world data assets are complex. Many users won’t realize how complex they are until they actually see the data for the first time.

While different RWD assets will follow different data models, they will usually be delivered in a series of tables, with each table representing a different type of data modality. For example, one table could represent demographic information in a one-row-per-patient (ORPP) format, while another table will represent longitudinal treatment information in a multiple-row-per-patient (MRPP) format.

All tables containing patient data will be linkable through a series of primary and foreign keys. A key is an attribute (or group of attributes) that can uniquely identify records in a table.

When dealing with RWD, it can be difficult for users to comprehend the relationships between tables and fields without a guide.

Entity Relationship Diagrams (ERDs)

An entity-relationship diagram (ERD) can be an invaluable tool in this regard. An ERD is a flow chart that illustrates how concepts, such as fields and tables relate to each other in a system. A well-crafted ERD can offer users a clear and concise visualization of their data model, enabling them to quickly and easily identify crucial relationships and dependencies between tables and fields.


While you can create an entity relationship diagram in any visual design tool, there are many tools available to help RWD users and providers create entity-relationship diagrams. Some, such as LucidChart and DBeaver, have functionality that allow you to automatically create them directly from the database itself. Others, such as DBDiagram, allow you to build them.

Free and Open-Source?
Best for
Creating visually appealing ERDs, either from scratch using a point-and-click interface or from an existing database
Creating an ERD from an existing database (MySQL, PostgreSQL, SQLite, ..)
Coders who want to quickly prototyping new ERDs, even if the database does not yet exist

For a video introduction to creating ERDs in DBeaver, check out the video below created by the DBeaver team:


RWD are complex. Providing users with tools to navigate that complexity will dramatically help them onboard to new RWD assets. One effective tool for helping users understand the tables underlying a RWD asset is an Entity Relationship Diagram (ERD). ERDs can be easily created using free and open-source tools.