Database Schema Managing Framework/Library

I'm looking for any database framework/library for .net which will act as a unified layer between an application and databases. Please note that I'm not interested in querying/updating data (there is plenty of DALs for that) but rather a framework which a开发者_运维知识库llows me to manage table schemas and indexes in a managed fashion (without using database specific SQL). I'm particularly interested in a library which supports Oracle, SQL Server and PostreSQL.

Well, I love SubSonic Migrations (that's a part of the SubSonic DAL which you can use standalone) but that doesn't support PostgreSQL.
So you should take a look at migratordotnet which works pretty much the same.

http://code.google.com/p/migratordotnet/