MYSQL 8.0 新特性-遞歸CTE

直接生成連續的數字

WITH recursive a (x) AS 
( SELECT 1 
UNION ALL
SELECT x + 1 FROM a WHERE x < 10 ) 
SELECT * FROM a;

層級查詢

測試數據示例

圖形展示如下

數據庫數據如下

id	name	parent_id
1	a
2	b	1
3	c	1
4	d	2
5	e	3
6	f	3

WITH RECURSIVE a(id,name,parent_id,path) AS 
(
SELECT 
	id,name,parent_id,name as path 
FROM 
	test1
--
UNION ALL
SELECT 
	a.id,a.name,b.parent_id,concat(b.name,"->",path) as path 
FROM 
	a,test1 b 
WHERE 
	a.parent_id is not null 
	and 
	a.parent_id=b.id
) 
SELECT id,name,path FROM a where parent_id is null;