在这个答案中,我询问了如何获取所有子节点以及对根节点的引用。现在我意识到我也需要相反的:
我想要所有的节点和所有的父母。
所以在这个简单的树中:
1 - 2 - 3
L - 4 - 5
L - 6
7 - 8
我想拥有
1 1;
2 2;
2 1;
3 3;
3 2;
3 1;
4 4;
4 2;
4 1;
5 5;
5 4;
5 2;
5 1;
6 6;
6 4;
6 2;
6 1;
7 7;
8 8;
8 7;
(顺序不重要)
这是获取相反结果的查询(从父级获取所有子级)。我试图玩它,但找不到解决方案。你能建议吗?
-- get all childs of all parents
WITH q AS
(
SELECT ID_CUSTOMER, ID_CUSTOMER AS root_customer
FROM CUSTOMERS c
UNION ALL
SELECT c.ID_CUSTOMER, q.root_customer
FROM q
JOIN CUSTOMERS c
ON c.ID_PARENT_CUSTOMER = q.ID_CUSTOMER
)
SELECT *
FROM q