WITH a AS (
	SELECT * FROM generate_series(ascii('A'), ascii('Z')) ascii
	UNION ALL SELECT * FROM generate_series(ascii('Ａ'), ascii('Ｚ'))
	UNION ALL SELECT * FROM generate_series(ascii('a'), ascii('z'))
), b AS (
	SELECT chr(ascii) FROM a
)
SELECT array_agg(chr ORDER BY chr) FROM b ;