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-- This function take two arguements. The first is the "given string" and
-- must not be null. The second arguement is the "compare string" and may
-- or may not be null. If the second string is null, the value returned is
-- 3, otherwise it is the levenshtein difference between the two.
CREATE OR REPLACE FUNCTION nullable_levenshtein(VARCHAR, VARCHAR) RETURNS INTEGER
AS $_$
DECLARE
given_string VARCHAR;
result INTEGER := 3;
verbose BOOLEAN := FALSE;
BEGIN
IF $1 IS NULL THEN
IF verbose THEN
RAISE NOTICE 'nullable_levenshtein - given string is NULL!';
END IF;
RETURN NULL;
ELSE
given_string := $1;
END IF;
IF $2 IS NOT NULL AND $2 != '' THEN
result := levenshtein_ignore_case(given_string, $2);
END IF;
RETURN result;
END
$_$ LANGUAGE plpgsql;
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