I have an assignment due in tomorow involving this and need help regarding part of it.

I need to create ERDs (entity relationship diagrams) for entities in a database, based on a zoo. The relationship in question is between animals and enclosures, basically I believe there to be a many-to-one relationship but a classmate believes it is a many-to-many relationship.

I think it's a many-to-one as an animal cannot be in more than one enclosure at once, and an enclosure can have multiple animals in it at once. although many animals can be in many enclosures an animal can still only be in one enclosure at once.

My classmate thinks it is a many-to-many as many animals can be put in many enclosures, in that an animal can be put in multiple enclosures and an enclosure can contain many animals.

My main argument for the many-to-one is that it should be modelled at any one time rather than for possibilities, as in this this book it gives an example of a many to many where it is modelled as 'at any one time'. (on page 356 to be specific)

Can anybody help me with this? Thanks in advance.


PS. I apologise for any sloppy writing.

Hi,

If you need to create ERDs (entity relationship diagrams) for entities in a database, u can try dezign for databases, it uses entity relationship diagrams (ERDs), provides the database designers with an effective tool to create ER ( entity relationship ) diagrams.