M:N relationships in ER diagram

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#1

Hi, I found this ER diagram online - therefore I am not sure if it’s 100% correct, I am currently working on a similar project for my school and it would help me to understand the M:N relationship in this case.

Snímek obrazovky 2020-11-18 v 10.40.11
Snímek obrazovky 2020-11-18 v 10.40.111222×746 132 KB

I understand the idea that one room can be reserved several times, however, I am getting a bit lost when it comes to the multiple relationships in the direction from the reservations table to the rooms table - how could I interpret this?

So I guess my question is - is this correct? and if yes, how can I interpret it?

Thank you so much for any help :slight_smile:

#2

I think this relation can be either, depending on your application.

You could say: A room can reserved several times, a reservation belongs to a room (M : N)

you could also make this relation M : M (many to many), then in one reservation you can book/reserve several rooms.