WITH RECURSIVE
unwound AS (
SELECT CONCAT(1,',',2,',',3) AS colors
UNION ALL
SELECT regexp_replace(colors, '^[^,]*,', '') colors
FROM unwound
WHERE colors LIKE '%,%'
)
SELECT regexp_replace(colors, ',.*', '') colors
FROM unwound
(https://stackoverflow.com/questions/17308669/what-is-the-opposite-of-group-concat-in-mysql)
