[ken]

My Mac app, Strukt, does a bit of this. The main problem is that the basics of the various databases don't align very well. The functionality that's common to all databases is quite weak. Even such things as case sensitivity are drastically different. And for many of the differences, there's simply no way to emulate the other's functionality, correctly and efficiently.

C compiles to assembly or machine code, and TypeScript compiles to JavaScript, and in both cases you have the full power of the level you're targeting, so it's fine. An RDBMS has very specific fast-paths that you really need to hit, or the whole exercise becomes pointless. It's like trying to write a 3D game in JavaScript without any way to access the GPU or even SIMD ops. We can do 3D games in JS today, but that's really only feasible because the browser vendors went and exposed the basic fast paths.