从层次表SQL中按关系顺序选择所有父项

Question

我有一个这样的表，在同一个表中有一个父子关系

AccountID|     ParentID     |   AccountName
----------------------------------------------
1       |   0       |   Root
2       |   1       |   Child1
3       |   1       |   Child2
4       |   2       |   Child3
5       |   4       |   Child1
6       |   5       |   Child1
7       |   6       |   Child1
8       |   6       |   Child1

因此，当我发送帐户ID 7 时，我必须按顺序获取表格，如孩子，父亲，祖父......那样..所以对于7，我需要得到所有的parets像此

AccountID
---------
    7
    6
    5
    4
    2
    1

所以最重要的一点是订单。它应该是从底层到下一层再高到下一层......

Answer 1

您可以使用recursive CTE：

declare @childAccID int
set @childAccID = 7  

;WITH Rec_CTE 
    AS(
        SELECT 1 AS Level, 
               tChild.*
        FROM dbo.TableName tChild
        WHERE tChild.AccountID = @childAccID

        UNION ALL

        SELECT Level + 1 AS Level, 
               parent.*
        FROM Rec_CTE tParent
        INNER JOIN  dbo.TableName parent 
          ON parent.AccountID = tParent.ParentID
    )
SELECT * FROM Rec_CTE
ORDER BY Level

DEMO

Answer 2

试试这个：

create table DemoTable
(
    accountid bigint
    ,parentid bigint
    ,accountname nvarchar(128)
)
insert DemoTable(accountid,parentid,accountname)
select 1, null, 'Root'
union select 2, 1, 'Child1'
union select 3, 1, 'Child2'
union select 4, 1, 'Child3'
union select 5, 2, 'Child1.1'
union select 6, 2, 'Child1.2'
go
declare @findMe bigint = 6;
with myCTE as
(
    select accountid,parentid,accountname,1 hierarchyLevel
    from DemoTable
    where accountid = @findMe

    union all

    select b.accountid,b.parentid,b.accountname, a.hierarchyLevel + 1
    from myCTE a
    inner join DemoTable b
    on b.accountid = a.parentid
)
select * from myCTE
order by hierarchyLevel