mysql字符串分割操作

SELECT \'1,2,3,4,5,6,7,8\' FROM dual;

-- 列转行分割
SELECT DISTINCT SUBSTRING_INDEX(SUBSTRING_INDEX(a.path,\',\',b.help_topic_id + 1),\',\',-1)  
FROM  
(SELECT GROUP_CONCAT(REPLACE(path,\'/\',\',\')) AS path FROM department b WHERE department_type = 1) a
JOIN 
mysql.help_topic b 
ON b.help_topic_id < (LENGTH(a.path) - LENGTH(REPLACE(a.path,\',\',\'\')) + 1);



-- 测试
SELECT DISTINCT SUBSTRING_INDEX(SUBSTRING_INDEX(a.path,\',\',b.help_topic_id + 1),\',\',-1) as path
FROM  
(SELECT \'1,2,3,4,5,6,7,8\' as path FROM dual) a
JOIN 
mysql.help_topic b 
ON b.help_topic_id < (LENGTH(a.path) - LENGTH(REPLACE(a.path,\',\',\'\')) + 1);

测试结果：

2022-12-23
2021-08-02
2021-09-02
2021-09-04
2022-12-23
2021-12-10
2022-02-11