No, and I'll give you an example. Take a simple relational table with some kind of constraint. Begin a transaction and insert some data into this table that vio

No, and I'll give you an example. Take a simple relational table with some kind of constraint. Begin a transaction and insert some data into this table that violates the constraint. What happens? Guess what, it depends on the db. Some databases/drivers will throw an exception immediately upon insert. Some will wait until the commit has occurred to throw the exception. Subtle differences like these exist all across the various relational db world. Not to mention that they all do locking and concurrency differently, which is probably the biggest problem.