SQL group_concat find_in_set 的使用

SELECT
p.id as pid,
p.code as code,
p.topic_name topic_name,
p.vm_id as vm_id,
GROUP_CONCAT(iso.iso_name SEPARATOR '-') as iso_name
 FROM `gf_practical_question` as p
LEFT JOIN gf_iso as iso  on  FIND_IN_SET(iso.id,p.vm_id)
GROUP BY p.id