Someone has to build it, but as long as you are using a popular DMBS the work is no doubt already done. All you need to do is stick your application-y bits in the middle – same as you have to do with GraphQL. Computers aren't exactly magic. It's all just 1s and 0s at the end of the day. You can do just about anything and make it work. But there are tradeoffs to different approaches. If GraphQL is the best choice for working with databases, why don't DMBSes use it natively?