递归CTE以查找父记录

Question

首先,我必须承认我不太熟悉sql server的递归CTE,但我认为这是最好的方法.

我有一张桌子tabData.它的PK被命名,idData并且有一个自引用FK fiData.

因此,fiData引用父记录并SELECT * FROM tabData WHERE idData=fiData返回父记录的所有数据.这很简单快捷.但是如何让自然顺序中的所有父母从特定记录中获取？假设有一个子节点(idData = 4)有3个父节点(第一个父节点是idData = 3的记录):

idData    fiData 
 4          3     
 3          2     
 2          1    
 1          NULL    

我认为递归CTE是要走的路,但我的语法并不好.那么实现返回所有父母的CTE的正确方法是什么？

我试过跟随,但它给了我错误的结果(3,4而不是3,2,1):(为了测试它我为你和你创建了一个临时表)

IF (NOT EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'dbo' AND  TABLE_NAME = 'tabData_Temp'))
BEGIN
 CREATE TABLE [dbo].[tabData_Temp](
  [idData] [int] NOT NULL,
  [fiData] [int] NULL,
   CONSTRAINT [PK_tabData_Temp] PRIMARY KEY CLUSTERED 
  (
   [idData] ASC
  )WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON)
 );

 ALTER TABLE [dbo].[tabData_Temp]  WITH CHECK ADD  CONSTRAINT [FK_tabData_Temp] FOREIGN KEY([fiData])
 REFERENCES [dbo].[tabData_Temp] ([idData]);
 ALTER TABLE [dbo].[tabData_Temp] CHECK CONSTRAINT [FK_tabData_Temp];

 INSERT INTO [dbo].[tabData_Temp](idData,fiData)VALUES(1,NULL);
 INSERT INTO [dbo].[tabData_Temp](idData,fiData)VALUES(2,1);
 INSERT INTO [dbo].[tabData_Temp](idData,fiData)VALUES(3,2);
 INSERT INTO [dbo].[tabData_Temp](idData,fiData)VALUES(4,3);
END

/* here comes the (not working) recursive CTE */
Declare @fiData int;
SET @fiData = 3;
WITH PreviousClaims(idData,fiData) 
AS(
     SELECT parent.idData,parent.fiData
     FROM tabData_temp parent
     WHERE parent.idData = @fiData

     UNION ALL

     SELECT child.idData,child.fiData
     FROM tabData_temp child
     INNER JOIN PreviousClaims parent ON parent.idData = child.fiData
)
SELECT idData
FROM PreviousClaims;
/* end of recursive CTE */


DROP TABLE [dbo].[tabData_Temp];

先感谢您.

Answer 1

改为:

INNER JOIN PreviousClaims parent ON parent.fiData = child.idData

给我你想要的结果.

Answer 2

你有向后联接.

改变这个

INNER JOIN PreviousClaims parent ON parent.idData= child.fiData 

对此

INNER JOIN PreviousClaims parent ON parent.fiData = child.idData