MySQL巧妙利用help_topic表把以逗号分隔的字符串转换成行

MySQL巧妙利用help_topic表把以逗号分隔的字符串转换成行

脚本：

1.  

   SELECT
     t1.*,
   	SUBSTRING_INDEX(
   		SUBSTRING_INDEX(
   			t1.phy_code,
   			',',
   			t2.help_topic_id + 1
   		),
   		',' ,- 1
   	) AS NEW_PHY_CODE
   FROM
   	so_invoice_t t1
   LEFT JOIN mysql.help_topic t2 ON t2.help_topic_id < (
   	LENGTH(t1.phy_code) - LENGTH(REPLACE(t1.phy_code, ',', '')) + 1
   )