Sql server SQL Server CTE递归-将树追溯到每个节点的特定树级别
我有两个表,Item(ItemID,CatID,Name)和Category(CatID,ParentID,Name,CatLevel)Category是一个目录树层次结构,项目可以位于其中。该表还跟踪每个节点所处的类别级别。下面是一个例子:Sql server SQL Server CTE递归-将树追溯到每个节点的特定树级别,sql-server,parent-child,common-table-expression,Sql Server,Parent Child,Common Table Expression,我有两个表,Item(ItemID,CatID,Name)和Category(CatID,ParentID,Name,CatLevel)Category是一个目录树层次结构,项目可以位于其中。该表还跟踪每个节点所处的类别级别。下面是一个例子: 1. Animal (CatLevel = 1) 2. Dog (CatLevel = 2) 3. Beagle (CatLevel = 3) 4. Labrador (CatLevel = 3)
1. Animal (CatLevel = 1)
2. Dog (CatLevel = 2)
3. Beagle (CatLevel = 3)
4. Labrador (CatLevel = 3)
5. Yellow (CatLevel = 4)
6. Chocolate (CatLevel = 4)
7. Black (CatLevel = 4)
8. Cat (CatLevel = 2)
9. Tabby (CatLevel = 3)
10. Horse (CatLevel = 2)
11. Stallion (CatLevel = 3)
我正在尝试提出一个查询,该查询将为我提供一个项目列表,其中包含常规CatID和我指定级别(例如,级别2)的CatID。示例输出:
Item CatID LevelTwoCatID
______ _____ _____________
Dog 2 2
Beagle 3 2
Labrador 4 2
Yellow 5 2
Chocolate 6 2
Black 7 2
Cat 8 8
Tabby 9 8
Horse 10 10
Stallion 11 10
我知道如何追溯到单个节点的类别,但我不知道如何进行更通用的查询,为每个节点提供“LevelTwoCatID”。以下是我如何做到这一点的:
WITH Tree AS
(
SELECT * FROM Category WHERE CatID = 6 -- Chocolate lab, change for some other
UNION ALL
SELECT * FROM Category AS a
INNER JOIN Tree t ON a.CatID = t.ParentID
)
SELECT * FROM Tree WHERE CatLevel = 2
如何获取所有节点/叶的CatLevel=2节点ID
谢谢 我知道这篇文章很老了,但我是这样写的 在我的表中有几个根类别,因此我使用@RootId来指定我要查找的根类别。根类别的ParentID设置为NULL 如果类别表中没有CatLevel列,cte树将为您创建该列。如果要经常使用查询,最好将其添加到表中(更新代码最后会被注释) 如果您希望拥有动态列数(不是像我的情况那样固定为5),请为其进行动态SQL查询
DECLARE @RootId INT, @SearchId INT
SET @RootId = 0
SET @SearchId = 0
--SELECT it.Id, it.ParentId, it.Name, it.RootId FROM ItemTree it
--WHERE (@RootId = 0 OR it.RootId = @RootId) AND (@SearchId = 0 OR it.Id = @SearchId)
;WITH Tree AS --gets category levels
(
SELECT 1 as CatLevel, it.Id, it.ParentId, it.Name, it.RootId
FROM ItemTree it WHERE it.ParentId IS NULL AND (@RootId = 0 OR it.RootId = @RootId) AND (@SearchId = 0 OR it.Id = @SearchId)
UNION ALL
SELECT t.CatLevel + 1 as CatLevel, it.Id, it.ParentId, it.Name, it.RootId
FROM ItemTree it
INNER JOIN Tree t ON it.ParentId = t.Id
WHERE (@RootId = 0 OR it.RootId = @RootId) AND (@SearchId = 0 OR it.Id = @SearchId)
----if CatLevel already exists in the table, just use it instead for better performance
--SELECT it.CatLevel, it.Id, it.ParentId, it.Name FROM ItemTree it
--WHERE (@RootId = 0 OR it.RootId = @RootId) AND (@SearchId = 0 OR it.Id = @SearchId)
)
, LeafIds AS --use it to show only leaf categories
(
SELECT DISTINCT Id FROM ItemTree it WHERE (@RootId = 0 OR it.RootId = @RootId)
EXCEPT
SELECT DISTINCT ParentId FROM ItemTree it WHERE (@RootId = 0 OR it.RootId = @RootId)
)
, LeafTree AS --prepare data for pivots
(
SELECT t.CatLevel, t.Id, t.ParentId, t.Name, Id AS LeafId
FROM Tree t --WHERE Id IN (SELECT Id FROM LeafIds)
UNION ALL
SELECT t.CatLevel, t.Id, t.ParentId, t.Name, lt.LeafId
FROM Tree t
INNER JOIN LeafTree lt ON lt.ParentId = t.Id
)
, TreeFinal AS --make pivots for Id and Name over same leafIds
(
SELECT t.*, pt1.[1] AS ID_1, pt1.[2] AS ID_2, pt1.[3] AS ID_3, pt1.[4] AS ID_4, pt1.[5] AS ID_5
, pt2.[1] AS Name_1, pt2.[2] AS Name_2, pt2.[3] AS Name_3, pt2.[4] AS Name_4, pt2.[5] AS Name_5
, ISNULL(pt2.[1], '') + ISNULL(' - ' + pt2.[2], '') + ISNULL(' - ' + pt2.[3], '') + ISNULL(' - ' + pt2.[4], '') + ISNULL(' - ' + pt2.[5], '') AS Path
FROM Tree t
JOIN (
SELECT LeafId, CatLevel, Id
FROM LeafTree
) source
PIVOT ( MAX(Id) FOR CatLevel IN ([1], [2], [3], [4], [5]) ) AS pt1 ON pt1.LeafId = t.Id
JOIN (
SELECT LeafId, CatLevel, Name
FROM LeafTree
) source
PIVOT ( MAX(Name) FOR CatLevel IN ([1], [2], [3], [4], [5]) ) AS pt2 ON pt2.LeafId = t.Id
)
--Use following to update CatLevel in your table, if it was not there before
--UPDATE it SET CatLevel = Tree.CatLevel FROM Tree JOIN dbo.ItemTree it ON it.Id = Tree.Id
SELECT * FROM TreeFinal ORDER BY Path
如果您提供
DECLARE@table\u var table(…)
语句和填充它们的脚本,您可能更容易得到响应。