I love the flexible schema capabilities of CouchDB and MongoDB, but I also love the relational 'join' capability of SQL Server. What I really want is the ability to have tables such as PERSON, COMPANY and ORDER that are basically 'open-schema' where each table has an ID but the rest of the columns are defined json-style {ID:12,firstname:"Pete",surname:"smith",height:"180"}, but where I can efficiently join PERSON to COMPANY either directly or via a many-to-many xref table. Does anyone know if SQL Server has any plans to incorporate 'open schema' in SQL, or whether Mongo or Couch have plans to support efficient joining? Thanks very much.
CouchDB offers a number of ways to establish relationships between your various documents/entities. Check out this article on the wiki to get started.
The tendency, when coming from a relational background, is to continue using the same terminology and mindset whenever you try to solve problems. It's very important to understand that NoSQL solutions are very different, otherwise they have no real purpose for existing. You should really seek to understand how these various NoSQL solutions work so you can compare them with your application's requirements to see if it's an appropriate fit.