我正在编写一个存储过程,它应该返回结果,并且相同的结果将作为输入传递给存储过程,并且递归应该在输入和输出在任何特定时间相同后停止。
下面是存储过程/函数和运行命令(存储过程的新特性)。
CREATE FUNCTION dbo.Ancestors (@List VARCHAR(MAX))
RETURNS TABLE
AS
RETURN
WITH CTE AS
(
SELECT DISTINCT Child AS RESULT FROM example WHERE Parent IN( SELECT Id =
Item FROM dbo.SplitInts(@List, ',')) or child IN (SELECT Id = Item FROM
dbo.SplitInts(@List, ','))
UNION ALL
SELECT DISTINCT Parent AS RESULT FROM example WHERE Parent IN( SELECT Id =
Item FROM dbo.SplitInts(@List, ',')) or child IN (SELECT Id = Item FROM
dbo.SplitInts(@List, ','))
)
SELECT RESULT FROM CTE
UNION
SELECT RESULT FROM CTE
GO
CREATE PROCEDURE GetAncestors (@thingID VARCHAR(MAX))
AS
SELECT RESULT FROM dbo.Ancestors(@thingID)
GO
EXEC GetAncestors @thingID = '100'
结果为- '100,101‘
EXEC GetAncestors @thingID = '100,101'
结果是- '100,101,102‘
EXEC GetAncestors @thingID = '100,101,102'
结果是- '100,101,102‘
我真正想要的是一次通过100、101或102的结果。
结果应为- '100,101,102‘
以下是示例表:
| Parent | Child |
|---------------------|------------------|
| 100 | 101 |
|---------------------|------------------|
| 101 | 102 |
|---------------------|------------------|
发布于 2018-05-30 22:54:55
看起来您需要一个简单的递归查询,该查询从给定节点开始向下遍历树。CTE
将返回(Parent, Child)
对的列表,因此我将它们合并在一起以获得单个节点的列表(并在此过程中删除重复的节点)。
请注意,该查询是递归的。CTE (公用表表达式)引用自身。
示例数据
我添加了更多的行来实际查看发生了什么。
DECLARE @T TABLE (Parent int, Child int);
INSERT INTO @T VALUES
(100, 101),
(101, 102),
(102, 103),
(103, 104),
(101, 108),
(108, 109),
(208, 209),
(209, 210);
查询
WITH
CTE
AS
(
SELECT
Parent, Child
FROM @T
WHERE Parent = 100
UNION ALL
SELECT
T.Parent, T.Child
FROM
CTE
INNER JOIN @T AS T ON T.Parent = CTE.Child
)
SELECT
Parent AS Result
FROM CTE
UNION
SELECT
Child AS Result
FROM CTE
;
结果
Result
100
101
102
103
104
108
109
您可以将查询放在存储过程中,如下所示:
CREATE PROCEDURE GetAncestors(@thingID int)
AS
BEGIN
SET NOCOUNT ON;
WITH
CTE
AS
(
SELECT
Example.Parent, Example.Child
FROM Example
WHERE Parent = @thingID
UNION ALL
SELECT
Example.Parent, Example.Child
FROM
CTE
INNER JOIN Example ON Example.Parent = CTE.Child
)
SELECT
Parent AS Result
FROM CTE
UNION
SELECT
Child AS Result
FROM CTE
;
END
GO
https://stackoverflow.com/questions/50604574
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