Many to Many relationships

Question

I want to express some many to many relatinships from a database in RDF format. For example user A rated Item B with value C.

How I have to express a many to many relationship in rdf?

I am thinking of using a blank node.

Example:

user:1 item:ratting [ _:1 item:id "5";item:ratting-number "10".] In order to express that user 1 rated item 5 with 10. Is there a better way to do that?

Accepted Answer

4

The approach you suggest is certainly a good option. Another popular approach is treating the relation as an object, e.g. for your example:

   _:1 a :item:Rating; 
       item:user user:1;
       item:id "5";
       item:rating-number "10" .

Though in this approach I would personally choose to create a new URI for the rating-object, rather than using a blank node, e.g. 'item:rating1'.

There is a W3C Note that discusses several approaches to modeling n-ary relations in RDF, which might be worth looking into.

link

answered 22 Feb, 18:17

Jeen Broekstra ♦
8.5k●3●12
accept rate: 32%

Thank you for your imidiate response! I was thinking to use a blank node because I dont have an actual URI for the relation

(22 Feb, 18:21) nikosdi

3

Well, you certainly can use blank nodes, nothing wrong with that in principle, but not having a URI is no excuse: simply create one on the fly :)

(22 Feb, 18:26) Jeen Broekstra ♦

Many to Many relationships

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