Entity Relationship: new syntax to allow attribute to be PK and FK at the same time

[RamanDamayeu]

Proposal

According to the documentation for Entity Relationship Diagrams we could add a key property to attributes and keys can be "PK" or "FK", for Primary Key or Foreign Key.

I would propose to add "PK/FK" or "PK,FK" to the chose as there is no restriction from modeling point of view that I know about for an attribute to play role of Primary Key and Foreign Key at the same time.

Example

In the following example CUSTOMER_STATUS.customer_number is a part of Primary Key for CUSTOMER_STATUS and also points to CUSTOMER.customer_number so plays the role of Foreign Key.

CUSTOMER {
		int customer_number PK
		string first_name
		string last_name
}

CUSTOMER ||--|{ CUSTOMER_STATUS : has_status
CUSTOMER_STATUS {
		int customer_number PK/FK
		datetime customer_status_start_datetime PK
		datetime customer_status_end_datetime
		string customer_status
}


### Screenshots

_No response_

[tomperr]

Good idea, I might take a look