Question

I need to manage hierarchy data storing in my database. But I have a problem now. Please see my example

I have a table called COMMON.TASK_REL

My second table is called Common. task

How can i return the parent task ID ? For example When i select C_Task_ID 307 then it will return the parent ID which is 304

Here is my query

  --Common task SQL modify --
WITH ctLevel
AS
(
SELECT
   C_TASK_ID AS Child
  ,P_Task_ID AS Parent
  ,common_task.TASK_SEQ AS taskOrder
  ,1 AS [Level]
  ,CAST(C_TASK_ID AS VARCHAR(MAX)) AS [Order]
  ,CAST (Replicate('.', 1) + common_task.TASK_NAME AS VARCHAR(25)) AS [Task_Name]
FROM   
       [COMMON.TASK_REL] as common_task_rel, 
       [COMMON.TASK] as common_task
WHERE common_task_rel.C_TASK_ID = common_task.TASK_ID
    and common_task.[TASK_TYPE] = 'B' AND common_task.[MODULE_CODE] = 'LWRPT' 
    AND common_task.[STATUS] <> 'D'
UNION ALL

SELECT 
   C_TASK_ID AS Child
  ,P_Task_ID AS Parent
  ,common_task.TASK_SEQ AS taskOrder
  ,[Level] + 1 AS [Level]
  ,[Order] + '.' + CAST(C_TASK_ID AS VARCHAR(MAX)) AS [Order]
  ,CAST (Replicate('.', [Level] + 1) + common_task.TASK_NAME AS VARCHAR(25)) AS [Task_Name]
FROM   [COMMON.TASK_REL] as common_task_rel
    INNER JOIN ctLevel
       ON ( P_Task_ID = Child ) , [COMMON.TASK] as common_task
WHERE common_task_rel.C_TASK_ID = common_task.TASK_ID
    and common_task.[TASK_TYPE] = 'B' AND common_task.[MODULE_CODE] = 'LWRPT'
    AND common_task.[STATUS] <> 'D'
)

-- Viewing Data
SELECT Child ,Parent ,taskOrder,Level,[Order],Task_Name
FROM   ctLevel  
GROUP BY Child ,Parent ,taskOrder,Level,[Order],Task_Name
order by [Order];
GO

Please help me modify the query. Thanks

Answer 1

Your query is quite complex so I will simplify some suggestions for you.

First some test data:

DECLARE @TASK_REL TABLE
    (
        ID INT,
        P_TASK_ID INT,
        C_TASK_ID INT
    )
INSERT INTO @TASK_REL
VALUES
    (21,NULL,300),
    (22,300,301),
    (23,300,302),
    (24,300,303),
    (25,NULL,304),
    (26,304,305),
    (27,304,306),
    (28,304,307)

DECLARE @Common TABLE
    (
        TASK_ID INT,
        TASK_Name VARCHAR(100),
        TASK_SEQ INT,
        MODULE_CODE VARCHAR(100),
        STATUS VARCHAR(5),
        TASK_TYPE VARCHAR(5)
    )

INSERT INTO @Common
VALUES
    (300,'Item1',0,'LWRPT','A','B'),
    (301,'Item 1.1',1,'LWRPT','A','B'),
    (302,'Item 1.2',2,'LWRPT','A','B'),
    (303,'Item 1,3',3,'LWRPT','A','B'),
    (304,'Item 2',0,'LWRPT','A','B'),
    (305,'Item 2.1',1,'LWRPT','A','B'),
    (306,'Item 2.2',2,'LWRPT','A','B'),
    (307,'Item 2.3',3,'LWRPT','A','B')

If you know that you just have one parent per child you can easily do this:

SELECT
    Common.TASK_Name,
    CommonParent.TASK_Name
FROM
    @Common AS Common
    JOIN @TASK_REL AS TASK_REL
        ON Common.TASK_ID=TASK_REL.C_TASK_ID
    JOIN @Common AS CommonParent
        ON ISNULL(TASK_REL.P_TASK_ID,TASK_REL.C_TASK_ID)=CommonParent.TASK_ID

Because you did a recursive cte on your tables. I think that you might want something like this:

;WITH CTE(C_TASK_ID,P_TASK_ID,TopParent)
AS
(
    SELECT
        TASK_REL.C_TASK_ID,
        TASK_REL.P_TASK_ID,
        C_TASK_ID AS TopParent
    FROM
        @TASK_REL AS TASK_REL
    WHERE
        TASK_REL.P_TASK_ID IS NULL
    UNION ALL
    SELECT
        TASK_REL.C_TASK_ID,
        TASK_REL.P_TASK_ID,
        CTE.TopParent
    FROM
        @TASK_REL AS TASK_REL
    JOIN CTE
        ON CTE.C_TASK_ID=TASK_REL.P_TASK_ID
)
SELECT
    Common.TASK_Name,
    CommonParent.TASK_Name
FROM
    CTE
    JOIN @Common AS Common
        ON CTE.C_TASK_ID=Common.TASK_ID
    JOIN @Common AS CommonParent
        ON CTE.TopParent=CommonParent.TASK_ID

You had a lot of joins in the recursive parts. I think you should one include the ones that are depended on the recursion and then join with it at the end.