WITH RECURSIVE split_csv(x, rest)
 AS (     SELECT SUBSTRING_INDEX(?, ',', 1),    SUBSTRING(?, FROM INSTR(?, ',') + 1)
UNION ALL SELECT SUBSTRING_INDEX(rest, ',', 1), SUBSTRING(rest, FROM INSTR(?, ',') + 1)
FROM split_csv)
SELECT something FROM atable WHERE data in (SELECT x FROM split_csv);