It's technicaly possible, but there would have to be some way for the user to define the relationship between the 2 fields. It would be nice to have, but it's probably not worth the trouble.
Ian G.
Ian - fair enough, but can you tell me what effect a relational database has on organising the MC library? That's really what I was trying to find out...
Assuming there's no facility for managing relationships, I don't think it'll have any effect. Let's use your example of an artist rating. I'd expect MC to have a table of artists - each artist will have a name and an ID. When you tag a file in the db, it's the ID that goes against the file, not the name. Suppose I now decide that "Yngwie Malmsteen" should be "Yngwie J Malmsteen", the name in the artist table gets changed, but nothing else since the files are associated with the name via the ID, and that didn't change - it's quick and efficient.
Suppose you now want to add your artist rating field - the normal way would be to add another field to the artist table. There's no tool to do that, so you have to create the field, manualy select all the Yngwie tracks and then update the artist rating field for each one. Not much of a task, but you'll have to do it each time you add a new track.
I guess MC could include a db management tool but, as TafkaFex has already said, it's a minefield! I think this a case where simplicity is more important than efficiency.
Ian G.