Many-to-many relationship: use associative table or delimited values in a column?

Question

Update 2009.04.24

The main point of my question is not developer confusion and what to do about it.

The point is to understand when delimite

Answer 1

The many-to-many mapping you are doing is fine and normalized. It also allows for other data to be added later if needed. For example, say you wanted to add a time that the category was added to the document.

I would suggest having a surrogate primary key on the document_category table as well. And a Unique(documentid, categoryid) constraint if that makes sense to do so.

Why are the developers confused?