Is it possible to write an entire web application in advanced SQL?

Question

PostgreSQL

I haven't worked much with any SQL extensions like PL/pgSQL, PL/Python, etc., so I was wondering - is it possible to write a simple web application entirely on such an extension? For example, a simple application in which the user can log in and make a search query in the database, the result of which is given to him in JSON - what can't be done with PL/Python in PostgreSQL?

Answer 1

It is possible, in theory, to keep all the business logic inside the DBMS. And I had such a project (with PostgreSQL).
And even sites can be written in assembler.
These two options are roughly identical in terms of convenience.