SELECT DISTINCT
SUBSTRING_INDEX( SUBSTRING_INDEX(专家组专业, '、', b.help_topic_id + 1 ), '、',- 1 ) AS split_title
FROM
( SELECT 序号, 专家组专业 FROM qmd_review_expert ) AS a
JOIN mysql.help_topic AS b
ON b.help_topic_id < (length( a.专家组专业 ) - length(REPLACE ( a.专家组专业, '、', '' ))+ 1)
ORDER BY split_title
// help_topic 是 mysql 系统库的表，主要是使用他的自增量 help_topic_id 字段
