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Chen’s database notation is useful for modeling the basics of entities and relationships, because it presents an abstract view of the associations.

These diagrams are a good entry step to understanding the database structure, especially for basic databases or examples. This notation is also well suited for brainstorming and quick diagraming.

Entities are represented by rectangles. Attributes are circular callouts to the entities. Relationships connect the entities with a diamond shape and descriptive text.

An example of a diagram that uses Chen's Database Notation.

For more information about entities, attributes, and relationships, see Create entity relationship diagrams

Create the diagram and entities

  1. In Visio, on the File menu, select New > Software, and then select Chen's Database Notation.

  2. Choose either Metric Units or US Units, and select Create.

  3. From the Chen's Database Notation stencil, drag an Entity shape onto the drawing page.

  4. Drag another Entity shape onto the drawing page to create a second entity.

  5. Drag a Relationship Connector shape onto the drawing page. Hover the shape over one of the entities, and release the mouse button. The connector is now connected to that entity. Drag the other end of the connector to the other entity to glue it there. 

  6. Optionally, you may right-clicking the connector and select Show Multiplicity.

  7. Drag a Relationship and place it on top of the connector line. To indicate that the relationship is optional, right-click it and select Set Identifying.

  8. To add an attribute to an entity, drag the Attribute from the Shapes pane toward the entity. When the connecting line is over the entity, a green highlight line encloses the entity, indicating that the attribute will be glued to the entity when you release the mouse button. 

  9. Right-click the attribute and choose from the options at the top of the menu:

    • Set Primary Key: An attribute that uniquely identifies a particular entity.

    • Set Multivalued Attribute: An attribute that can have many values—that is, there are many distinct values entered for it in the same column of the table. 

    • Set Derived Attribute: An attribute whose value is calculated, or derived, from other attributes. A derived attribute may or may not be physically stored in the database.

    • Set Required: A required attribute must have a value in it, while an optional attribute may not have a value in it and can be left blank.

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