27 lines
694 B
Plaintext
27 lines
694 B
Plaintext
# n is normally an integer but can be anything
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create or replace function sum_digits(n) as (
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regexp_extract_all(n::VARCHAR, '.')
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.list_transform( x -> (ascii(x) - 48) % 10)
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.list_sum()
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);
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# n should be an integer
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create or replace function digital_root(n) as table (
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with recursive cte as (
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select 0 as ix, n as sum
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union all
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select ix+1, sum_digits(sum)
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from cte
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where length(sum::VARCHAR) > 1
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)
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select last(ix order by ix) as persistence,
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last(sum order by ix) as "digital root",
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from cte
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);
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## Examples:
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from (select unnest(range(0, 4)) as i,
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unnest([627615, 39390, 588225, 393900588225]) as n),
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(from digital_root(n))
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order by i;
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