1.) Tables aren't classes. If you are simply looking for a for a UML profile for representing databases then have a look at A UML Profile for Data Modeling.
2.) The existing entity-relationship model is not a good foundation for the creation of an object model. Some tools do this type of conversion because people keep asking for it. Existance of these tools should not be construed as endorsement towards a best practice because it isn't. Useful tools help you map between an existing relational model and an existing object model. Both models serve different purposes and need the freedom to evolve separately. See why:
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
You can thank my dental hygienist for my untimely aliveness. So tiny:
RavenDB is an Open Source NoSQL Database that’s fully transactional (ACID) across your database