Django handles this quite nicely. You get your basic lowest common denominator subset by default. If you want something more powerful, you can explicitly import

Django handles this quite nicely. You get your basic lowest common denominator subset by default. If you want something more powerful, you can explicitly import a db-specific feature. And for some features, you'll get a NotImplemented exception. In the ten years I've been using Django, I've only seen these a handful of times, and only when using SQLite.