mysql使用mysql.help_topic表实现一行转多行功能

使用到数据库自带的mysql.help_topic表来属性拆分，help_topic表就是实现行转列功能

SELECT
	SUBSTRING_INDEX(
		SUBSTRING_INDEX('1,2,3,4,5',',',help_topic_id + 1),',' ,- 1) lzh
FROM
	mysql.help_topic
WHERE
	help_topic_id < (LENGTH('1,2,3,4,5')) - LENGTH(REPLACE ('1,2,3,4,5', ',', '')) + 1;