square.sql

with recursive

limitxy AS (SELECT * FROM (VALUES(20, 20)) AS t (x,y)),

formula(n, x, y, c) AS (
  VALUES(0, 0, 0, '')
UNION ALL
  SELECT n+1,
(SELECT x FROM (SELECT n % (SELECT x FROM limitxy) AS x, n / (SELECT x FROM limitxy) AS y) AS xy),
(SELECT y FROM (SELECT n % (SELECT x FROM limitxy) AS x, n / (SELECT x FROM limitxy) AS y) AS xy),
CASE WHEN (
  SELECT (
    ((point.x = 5 OR point.x = -5) AND -5 <= point.y AND point.y <= 5) OR
      ((point.y = 5 OR point.y = -5) AND -5 <= point.x AND point.x <= 5)
  )
    FROM (
    SELECT x - (SELECT x/2 FROM limitxy) AS x, y - (SELECT y/2 FROM limitxy) AS y
  FROM (SELECT n % (SELECT x FROM limitxy) AS x, n / (SELECT y FROM limitxy) AS y) AS xy
) AS point
)
then '#'
ELSE ' '
END
FROM formula WHERE n < (SELECT x * y FROM limitxy)
),
mkstring(num, s) AS(
  VALUES(0, '')
UNION ALL
  SELECT num + 1, (SELECT ARRAY_TO_STRING(ARRAY_AGG(c), '') FROM formula WHERE num = formula.y) FROM mkstring WHERE num < (SELECT y FROM limitxy)
)
SELECT s FROM mkstring WHERE num != 0;


          s
----------------------





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