Recursive Fibonacci sequence up to nth number in SQL

fib.sql

WITH RECURSIVE fib (a, b, n) AS (
    SELECT 0, 1, 1
  UNION ALL
    SELECT b, a+b, n+1 FROM fib
)
SELECT a FROM fib WHERE n<=8;

Here is another implementation I made today in plpgsql, tail recursion:

CREATE OR REPLACE FUNCTION fibTailRecursive(n INTEGER, prevFib INTEGER DEFAULT 0, fib INTEGER DEFAULT 1)
RETURNS INTEGER AS $$
BEGIN
  IF (n = 0) THEN
    RETURN prevFib;
  END IF;
  RETURN fibTailRecursive(n - 1, fib, prevFib + fib);
END;
$$ LANGUAGE plpgsql;

When I was coding my solution in TablePlus it DID notice that it's outer scope only cares about n=8. That's why it ran forever for you but not for me. TablePlus is smart about that stuff. But I see what you mean, haha.

Recursion has sort of come under the dominion of functional programming, and this is a clearly non-functional approach to recursion. Do you have Hangouts? I'd love to chat more. It warms my heart to see people pursuing curiosity and intellectual gratification.