How to Make an ER Diagram in Visio (Crow's Foot Notation)
An entity relationship diagram shows the things a system stores data about and how they relate. Learn crow's foot notation and draw a customer, order and payment ER diagram in Visio, step by step.
Step by step
Intro
- ER diagram in Visio. An ER diagram shows what a system keeps data about, and how those things relate. Let's draw one in Visio with crow's foot notation, for a simple online shop.
- Crow's Foot stencil. I've opened the Crow's Foot Database Notation stencil. We'll use two shapes, the entity and the relationship.
Entities
- Entity. An entity is a thing we store data about. Drop one on the page and name it customer. The first row is the primary key, the field that makes each customer unique. Now an order entity. Each order has its own ID, a date, and the customer it belongs to.
Relationships
- Relationship. Connect them with a relationship. Read it out loud. One customer places zero or many orders.
- Reading crow's foot. The two lines on the customer end mean one and only one. The circle and the crow's foot on the order end mean zero or many. That's the whole trick of crow's foot notation.
A third entity
- A third entity. Customers pay for their orders, so add a payment entity. It keeps the order ID it belongs to.
- Relationship. Connect order to payment. One order has zero or many payments, for example a deposit and a final payment.
- Done. Click away to see the finished diagram.
3 ER rules
- 3 ER rules. Three rules. Entities are nouns, written in the singular. Every entity needs a primary key. And always read each relationship out loud, in both directions, to check it makes sense. Subscribe for more Visio tips for business analysts.
