mysql的字段拆分和合并

SELECT a.s_id as '编号',
SUBSTRING_INDEX(SUBSTRING_INDEX(a.s_name,',',b.help_topic_id + 1),',',-1) as '特征',
CONCAT(a.s_id,SUBSTRING_INDEX(SUBSTRING_INDEX(a.s_name,',',b.help_topic_id + 1),',',-1),'哈哈')
FROM yoyo a
JOIN mysql.help_topic b ON
b.help_topic_id < (LENGTH(a.s_name) - LENGTH(REPLACE(a.s_name,',',''))+1);


-- 非空情况

CONCAT(IFNULL(t1.CITYNAME,''),IFNULL(t1.AREANAME,''),IFNULL(t1.STREETNAME,''),IFNULL(t1.ADDRESS,''))addressDetail

 

 

 

 

SELECT s_id as '编号',GROUP_CONCAT(s_name) as '特征' FROM coco GROUP BY s_id