Relational algebra didn't evolved into a relational programming language. SQL is merely a query language. The recursion is horribly done and there is no type systems. Imagine this, Friends(a: Person, b: Person) defines the relationship and the foreign keys at the same time. It makes the reasoning easier too. mary.Friends.Friends get all friends of friends of mary who is a Person. SQL requires you to write a lot of joins to achieve this. Error prone coding experience. That is why there are ORMs which end up with half baked solutions.

In fact, logic programming language and SQL should consolidate into a relational programming language. Every thing we write as a program, automatically supports persistent and distributed storage. It can also support probabilistic computation to have machine learning involved. Then we will have a complete data driven software solution.

Unfortunately, right now, we cook everything up with SQL, python, operational DBs, analytics DBs, Spark, Tensorflow.

It could have been a better place.