Besides a declarative language, is SQL a functional language?

Question

Why yes or why not?

Answer 1

Not generally speaking, as without extensions to the syntax (e.g. PL/SQL, T-SQL), you can't write functions.

But it is certainly very expression-oriented, which is a feature it has in common with functional languages.

Answer 2

Are functions first-class objects in SQL? hardly. So I'd say no.

Answer 3

Declarative and functional? That would be a spreadsheet.

Answer 4

There's no single true definition of what a functional language is (or for that matter, what a procedural or object-oriented one is).

But I can't really think of much that points to SQL being functional. It doesn't have functions, it doesn't have recursion, it doesn't have closures, it doesn't have nested functions, it doesn't have functions as first-class types.

A more commonly asked question is whether SQL is a programming language at all. It's not turing-complete.

Answer 5

Since the point of a functional language is that you program with, well, functions, I would say no. SQL is programming with relations (if you can even call SQL a programming language - in it's basic form, SQL is not Turing complete).

Answer 6

I think SQL and functional languages are very different from each other. In a functional language computation is done by evaluating functions. Functions do not mutate state. All they do is compute a value from their arguments. I other words, functions do not cause side-effects. Functional languages are general purpose.

SQL is a language designed for dealing with relational database management systems. It can be viewed as a Domain Specific Language. It is designed to work on "sets" of data. It can mutate global state (i.e, the database) by using commands like UPDATE. There is no concept of functions getting evaluated to a value. As far as I understand, SQL is not even Turing complete.