In Entity Relationship Model, can the supporting (or identifying) relationships of the weak entities be many-many or one-one rather than many-one?
Suppose I have a customer entity (C), a video entity (V) and a weak entity reservation (R). C - R has a one-many relationship and it's a supporting relationship for R. However between V - R the same one-many relationship wouldn't make sense, since a video shouldn't appear in two different reservations.
So I wonder if a one-one relationship can be a supporting one for the weak entity? Or should it be a normal one-one instead of a supporting one?