Create Multiple Diagrams for Entity Data Model in Entity Framework:

The Entity Data Model (EDM) for the large database will display all the entities into a single visual designer. This makes it difficult to organize and identify entities on the designer. Visual Studio (2012/2015/2017) provides a facility to split the visual representation of an Entity Data Model into multiple diagram.

To create a new diagram for you EDM, open Model Browser by right cliking on the designer surface and select Model Browser on the context menu. In the Model Browser, you will see an exsting diagram for your EDM. Create a new diagram by right clicking on the Diagrams node in the Model Browser and select 'Add New Diagram', as shown below.

Entity Framework 5.0 Tutorial

This will create a new diagram. You may rename the diagram as shown below.

Entity Framework 5.0 Tutorial

Now, you can drag and drop entity types from Model browser to new diagram, as shown below:

Entity Framework 5.0 Tutorial

You can also move entities from an existing diagram to a new diagram without creating a new diagram first. For example, if you want to move Teacher and Course entity type to a new diagram, then select those entities in an existing diagram and right click and select 'Move to New Diagram' from the context menu:

Entity Framework 5.0 Tutorial

It will create a new diagram and move Teacher and Course entities to a new diagram as shown below:

Entity Framework 5.0 Tutorial

So, in this way you can create a new diagram from an existing diagram.

Include Related Entities:

You can also include the related entities of a particular entity in one diagram. For example, right click on Student entity → select 'Include Related'. The Standard and Course entities will also be included, because Student contains reference property of Standard and Course.

Entity Framework 5.0 Tutorial

This will include related entities in the same diagram as shown below.

Entity Framework 5.0 Tutorial

Additionally, you can also move properties up or down by right clicking on the property → select Move Property → select UP/Down etc. as shown below:

Entity Framework 5.0 Tutorial

Difference between Delete Entity and Remove Entity:

You can remove the entity from the diagram by right clicking on entity and selecting 'Remove from diagram'.

Entity Framework 5.0 Tutorial

Remove from Diagram will only remove the entity from the diagram whereas 'Delete from Model' will delete the entity from the EDM and you won't be able to use that entity at all.