for experts about operations to data access in ER diagram

[zio_mangrovia]

If I have ER schema where I have:

2 entity: Room, Hotel
1 relationship: Link
Cardinality about Room side is (1:1) each room belongs only to one hotel
Cardinality about Hotel side (1:N) each hotel can have more than one
Hotel has code attribute as primary key.
Room has foreign key: room number attribute + hotel code.

see: https://ibb.co/f471m9Q

My doubt is about operation to evaluate performance database before to migrate to logical model, infact this step is necessary during ER restructuring.
My question:

I have hotel code (e.g. hotel Europe) and I need to know what rooms numbers are in that hotel, I have to access only to relationship "link" or I need to access to Room entity too?
I'd like to understand if, at level ER diagram, "link" relationship contains number attribute too. Thanks

[skhanal]

Is Room Number an attribute of Room entity?

[zio_mangrovia]

Is Room Number an attribute of Room entity?

Yes, It is.

ers.PNG

[skhanal]

In ER diagram, link does not tell you about attributes, so you have to read Room entity for Room number. When you convert this to physical model, there is no physical representation for 1-1 and 1-m relations.