2.1.5 Entity Key

A Key element describes which Property elements form a key that can uniquely identify instances of an EntityType. Any set of non-nullable, immutable, scalar type declared properties can serve as the key.

The following is an example of the Key element.

       <PropertyRef Name="CustomerId" />

The following rules apply to the Key element:

  • Key can contain any number of AnnotationAttribute attributes. The full names of the AnnotationAttribute attributes cannot collide.

  • Key MUST have one or more PropertyRef child elements.

  • Each PropertyRef child element names a Property of a type that is equality comparable.

  • In CSDL 2.0 and CSDL 3.0, Key can contain any number of AnnotationElement elements.


All child elements are to appear in the order indicated.