数据符号给出层级??为什么p001是2级?没有明白
SELECT
SUBSTRING_INDEX(SUBSTRING_INDEX( a.`name`, ',', b.help_topic_id + 1 ), ',',-1 ) name
FROM
(select replace(replace(replace(replace('(1+2)-(3+4*6)','+',','),'-',','),'*',','),'/',',') as name) a
JOIN mysql.help_topic b ON b.help_topic_id < ( LENGTH( a.`name`) - LENGTH( REPLACE ( a.`name`, ',', '' ) ) + 1 );