Is there an "object database" addon for SQL or MySQL, etc?

I'm wondering if there is an "object database" addon layer for SQL server 2008 (or MySQL, etc). Ive become used to using db4o (an object database), where you can write the contents of any object(s) to the database with a single command, without worrying about ponderously creating the database schema, LINQ-to-Entities style.

I'm sure its possible to do this - is there any addon which allows you to write a .NET object straight to a database, with a single command (no table setup), then query these 开发者_开发问答objects with LINQ?

See How to I serialize a large graph of .NET object into a SQL Server BLOB without creating a large buffer?