What does HackerNews think of PetaPoco?
Official PetaPoco, A tiny ORM-ish thing for your POCO's
Everyone should know sql, but choose an ORM (micro-ORM) that doesn't have any abstractions, and gets data in and out. There are many solutions that offer you this without needing to write any SQL.
https://github.com/CollaboratingPlatypus/PetaPoco
https://github.com/ServiceStack/ServiceStack.OrmLite
Micro ORMs is where it's at. You're asking for trouble if you choose something that does WAY more than it should, like Entity Framework.
It's the perfect type-safe abstraction on top of raw SQL.
https://github.com/ServiceStack/ServiceStack.OrmLite
https://github.com/CollaboratingPlatypus/PetaPoco
Any errors you get are likely a result of the underlying database/provider (foreign key constraints, etc).
You should never write raw SQL (if possible). You don't need an ORM to achieve that.