我在 SQL Server 中有一个层次结构,有多个父级,但似乎无法获得我需要的结果集。
这是我到目前为止。
DECLARE @Table TABLE (ChildId varchar(max), ParentId varchar(max))
INSERT INTO @Table (ChildId,ParentId)
VALUES
('England',NULL),
('Cities',NULL),
('Towns',NULL),
('South West','England'),
('Bristol','South West'),
('Bristol','Cities'),
('Suburb','Bristol'),
('Thornbury','South West'),
('Thornbury','Towns');
WITH CTE (ChildId, ParentId, Level)
AS (
SELECT
ChildId,
ParentID,
0
FROM @Table
WHERE ParentID IS NULL
UNION ALL
SELECT
r.ChildId,
r.ParentId,
ct.Level + 1
FROM @Table r
JOIN CTE ct
ON ct.ChildId = r.ParentId
)
SELECT * FROM CTE order by childId, level
这给了我这个结果集:
ChildId | ParentId | Level
Bristol | Cities | 1
Bristol | South West | 2
Suburb | Bristol | 2
Suburb | Bristol | 3
Cities | NULL | 0
England | NULL | 0
South West | England | 1
Thornbury | Towns | 1
Thornbury | South West | 2
Towns | NULL | 0
但我也想要祖 parent 、曾祖 parent 和曾曾祖 parent (等):
ChildId | ParentId | Level
Bristol | Cities | 1
Bristol | South West | 2
Bristol | England | <------------------------
Suburb | South West | <------------------------
Suburb | England | <------------------------
Suburb | Cities | <------------------------
等等。
最佳答案
您尝试做的事情至少在某种程度上类似于 Ranganathan 的分类。在这种情况下,您必须在层次结构中向上,而不是向下:
with cte as (
select t.ChildId, t.ParentId, 0 as [Lvl]
from @Table t
where t.ParentId is not null
union all
select c.ChildId, t.ParentId, c.Lvl + 1
from @Table t
inner join cte c on c.ParentId = t.ChildId
where t.ParentId is not null
)
select * from cte c order by c.ChildId, c.Lvl, c.ParentId;
编辑:更新了 CTE 递归部分中的
WHERE
子句。看起来这是最初尝试的一些剩余物,我忘记考虑了。
关于sql - 在 SQL Hierarchy CTE 中显示所有子级和孙级,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/27044907/