Mandelbrot SQLite query example from https://www.sqlite.org/lang_with.html#outlandish_recursive_query_examples

mandelbrot.sql

-- Example from https://www.sqlite.org/lang_with.html#outlandish_recursive_query_examples
CREATE TABLE mandelbrot AS WITH RECURSIVE
  xaxis(x) AS (VALUES(-2.0) UNION ALL SELECT x+0.05 FROM xaxis WHERE x<1.2),
  yaxis(y) AS (VALUES(-1.0) UNION ALL SELECT y+0.1 FROM yaxis WHERE y<1.0),
  m(iter, cx, cy, x, y) AS (
    SELECT 0, x, y, 0.0, 0.0 FROM xaxis, yaxis
    UNION ALL
    SELECT iter+1, cx, cy, x*x-y*y + cx, 2.0*x*y + cy FROM m 
     WHERE (x*x + y*y) < 4.0 AND iter<28
  ),
  m2(iter, cx, cy) AS (
    SELECT max(iter), cx, cy FROM m GROUP BY cx, cy
  ),
  a(t) AS (
    SELECT group_concat( substr(' .+*#', 1+min(iter/7,4), 1), '') 
    FROM m2 GROUP BY cy
  )
SELECT group_concat(rtrim(t),x'0a') FROM a;

Demo in Datasette Lite: https://lite.datasette.io/?sql=https%3A%2F%2Fgist.githubusercontent.com%2Fsimonw%2F14cab44a5a169806263bcb8e481944aa%2Fraw%2F88b237ba019e5330fcb6f66ce0c8f626a11df097%2Fmandelbrot.sql#/data/mandelbrot