I've heard a lot lately that SQL is a terrible language, and it seems that every framework under the sun comes pre-packaged with a database abstraction layer.
In my experience though, SQL is often the much easier, more versatile, and more programmer-friendly way to manage data input and output. Every abstraction layer I've used seems to be a markedly limited approach with no real benefit.
What makes SQL so terrible, and why are database abstraction layers valuable?