如何在SQL顯示遞歸的parentID在單個列

Question

下面是表的結構例：

ID Name  ParentID 
----------------------- 
1  Ancestor  NULL 
2  GrandFather 1 
3  GrandMother 1 
4  Child   3 

我想編寫一個查詢，將返回

ID  Name  Family 
---------------------------- 
1  Ancestor 
2  GrandFather Ancestor 
3  GrandMother Ancestor 
4  Child  Ancestor^GrandMother 

棘手部分是我想要以自上而下的順序顯示所有行的家族。

如果任何人都可以在正確的方向指向我，我們將不勝感激:)

編輯::這是真正的查詢，但它遵循了同樣的想法。它返回的行錯誤：marketparent.family + '^' + t2.marketGroupName，因爲它無法找到marketparent

WITH marketparent (marketGroupID,parentGroupID, marketGroupName,family) 
AS 
(
SELECT marketGroupID, 
     parentGroupID, 
     marketGroupName, 
     '' as family 
FROM EVE.dbo.invMarketGroups 
WHERE parentGroupID IS NULL 
UNION ALL 

    SELECT t2.parentGroupID, 
    t2.marketGroupID, 
    t2.marketGroupName, 
    marketparent.family + '^'+ t2.marketGroupName 
    FROM EVE.dbo.invMarketGroups as t2 
    INNER JOIN marketparent as mp 
    ON mp.marketGroupID = t2.parentGroupID 
) 

-- Statement using the CTE 

SELECT TOP 10 * 
FROM marketparent; 

Answer 1

你沒有指定你的DBMS，所以我假定PostgreSQL的

WITH RECURSIVE fam_tree (id, name, parent, family) as 
(
    SELECT id, 
     name, 
     parentid, 
     ''::text as family 
    FROM the_unknown_table 
    WHERE parent IS NULL 

    UNION ALL 

    SELECT t2.id, 
     t2.name, 
     t2.parentid, 
     fam_tree.family || '^' || t2.name 
    FROM the_unknown_table t2 
    INNER JOIN fam_tree ON fam_tree.id = t2.parentid 
) 
SELECT * 
FROM fam_tree; 

這是標準的SQL（除了::text類型轉換），它們應該能夠在大多數現代DBMS上進行很少的更改。

編輯：

對於SQL Server，你就需要更換與微軟的非STANDAR +標準concatention字符（你需要刪除它是由標準，但一些奇怪的原因所需要的recursive關鍵字被SQL Server拒絕）

WITH fam_tree (id, name, parent, family) as 
(
    SELECT id, 
     name, 
     parentid, 
     '' as family 
    FROM the_unknown_table 
    WHERE parent IS NULL 

    UNION ALL 

    SELECT t2.id, 
     t2.name, 
     t2.parentid, 
     fam_tree.family + '^' + t2.name 
    FROM the_unknown_table t2 
    INNER JOIN fam_tree ON fam_tree.id = t2.parentid 
) 
SELECT * 
FROM fam_tree; 

Answer 2

您可以使用遞歸Common Table Expression。

declare @T table 
(
    ID int, 
    Name nvarchar(15), 
    ParentID int 
); 

insert into @T values 
(1,  N'Ancestor',  NULL), 
(2,  N'GrandFather', 1), 
(3,  N'GrandMother', 1), 
(4,  N'Child',   3); 

with C as 
(
    select T.ID, 
     T.Name, 
     T.ParentID, 
     cast(N' ' as nvarchar(max)) as Family 
    from @T as T 
    where T.ParentID is null 
    union all 
    select T.ID, 
     T.Name, 
     T.ParentID, 
     C.Family+'^'+C.Name 
    from @T as T 
    inner join C 
     on T.ParentID = C.ID 
) 
select C.ID, 
     C.Name, 
     stuff(C.Family, 1, 2, '') as Family 
from C; 

Answer 3

select T.ID, T.Name, (select name from table where ID=T.ParentID)as Family 
from table T