Types of Entities and Fields in CDS

Types of Entities

Standard

These are entities that are always created for every instance of the Common Data Service database. So as mentioned before when an instance is generated, a set of standard entities are also set-up so the user can immediately begin to extend on the database and draw relationships. As such, for standard entities you are able to add more fields to any entity but you can only delete fields from custom entities.

Complex

With complex entities, they contain more complex variable data. This can be things like:

• Server-side business logic

• Real-time workflows

• Plugins

Complex entities are usually present in things like Dynamics365 apps.

Fields

Fields are a level below entities - so entities are made up of various fields. These are like the attributes of objects and so they hold pieces of information within a record that is kept inside an entity. You can think of fields as columns in Excel. It's one data entry which can hold a specific type of data.

A field also has type. This means that the type of data within a field matches the type of the field. For example, if you have a field that is of Type: Date then you can store data like 16-Sep if your solution requires data for Dates. Similarly, if your solution has numbers then you would use a Field that has Type: Number in order to store your data.

The number of fields within an entity can vary depending on your situation. It very well range from a single digit to a few hundred. However, if you find yourself exceeding several hundred fields, then it's probably more ideal to think about how to restructure your database because when you get to that point, there is definitely a more ideal solution.

With each instance of a Common Data Service Database, you're equipped with standard entities consisting of standard fields right off the bat. It is generally best practice to utilise the standard entities FIRST before deciding to create new entities. You can easily rename the entities to fit your solution context - so always utilise the standard entities wherever you can!