Is there a declarative language for data definitions?

Question

Reading about WPF and thinking about my application's data store at the same time led me to wonder if there are any languages or tools that allow you to define relational data in a declarative way?

A shallow Google search suggests no such thing exists. Yet it seems so obviously useful. The kind of tool I have in mind would declaratively describe (at least) entities, relationships and views is a platform-agnostic way that would act as an abstraction layer between data-driven applications and their datastores.

Does any such tool exist?

Answer 1

hibernate mapping ? http://docs.jboss.org/hibernate/core/3.3/reference/en/html/tutorial.html

Answer 2

It's not exactly platform-independent, but the ADO.NET DataSet's schema pretty much does exactly what you're describing. It's a declarative description of an XML format for representing relational data. It doesn't include views, but it does include entities and relationships.

It's not platform-independent, but on the other hand, it exists.