An entity relationship diagram (ERD) illustrates how different entities (such as customers and products) relate to each other in a database.
Here are the the three primary parts of an ERD:
Entities: The tables in your database. Entities are nouns. Common classifications are concepts, locations, roles, events, and things.
Attributes: Facts that describe each table. They are nouns, and they often become the columns of tables.
Relationships: Relationships are verbs. They indicate the associations between entities.
Visio has stencils for three kinds of entity relationship diagrams. Each uses specific symbols to represent entities and the relationships between them. See the following support articles for more details about these types of diagrams:
Visio also supports the ability to reverse-engineer a database model from an existing database. See Create a database model for more information.
Visio also offers a stencil that lets you create a data-flow diagram, which provides information about the outputs and inputs of each entity and the process itself. See Create a data flow diagram for more information.
Visio for the web has stencils for two kinds of entity relationship diagrams. Each uses specific symbols to represent entities and the relationships between them. See the following support articles for more details about these types of diagrams:
Note: Creating and editing entity relationship diagrams on Visio for the web requires a Visio Plan 1 or Visio Plan 2 license, which is purchased separately from Microsoft 365. For more information, contact your Microsoft 365 admin. If your admin has turned on "self-service purchasing," you can buy a license for Visio yourself. For more details, see Self-service purchase FAQ.