# n is assumed to be a non-negative integer
CREATE OR REPLACE FUNCTION binary_digits(n) as (
  WITH RECURSIVE cte(num, str) as (
    -- Base case
    SELECT n, ''
    UNION ALL
    -- Recursive case: divide by 2 and build the binary string
    SELECT num // 2, (num % 2) || str
    FROM cte
    WHERE num > 0
  )
  SELECT CASE WHEN str = '' THEN '0' ELSE str END
  FROM cte
  WHERE num = 0
  LIMIT 1
);

select n, binary_digits(n)
from (select unnest(range(0, 6) || [50, 9000]) as n);

.maxwidth 200
select n, binary_digits(n) from (select 123456789123456789123456789123456789 as n)