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Common ERD Mistakes
How to create entity relationship diagrams that make sense
Data modelling is not only for data architects and software engineers. Anyone who works with data, including data analysts, business analysts, and business intelligence designers, needs to understand and be able to create at least simple data models.
Even simplistic entity relationship diagrams (ERDs) can help support analysis and data discovery, identify crucial relationships and clarify important groups of data.
Sometimes, a conceptual model is sufficient, and on other occasions, a starter logical model with a few attributes will work best to support business & data analysis activities. See this article and video if you want to learn more.
As I taught cohort after cohort of students in a business analytics program, I saw them struggle with the same questions, and make the same mistakes over and over when creating their first ERDs. This article is a summary of typical ERD mistakes and how to avoid them.
Before we get there, let’s recap the main elements of the diagram.
ERD Building Blocks
Entity: A person, thing, event or concept about which the business keeps data.
