Question

我在stackoverflow本身 (Question before)中已经回答了问题。所以我只是因为一个根元素

而重复了一些变化和麻烦的问题

我有一个像这样的SQL表

ID        Name        ParentID
------------------------------
0        Users         NULL
1        Alex          0
2        John          0
3        Don           1
4        Philip        2
5        Shiva         2
6        San           3
7        Antony        6
8        Mathew        2
9        Cyril         8
10       Johan         9
-------------------------

我正在寻找像这样的外线

如果我传递ID 7,10,1

输出表将是

ID          Name           Relation
------------------------------------
7           Antony         Alex->Don->San->Antony
10          Johan          John->Mathew->Cyril->Johan
1           Alex           -

从上面的回答我要强调的是它不应该考虑ID为0且parentid为null的最顶层节点用户。因此对于ID 1，它只返回一个空字符串表示关系或只是连字符（ - ） 如何使用CTE

实现这一目标

Answer 1

基于prev answer：

DECLARE @t table (ID int not null, Name varchar(19) not null, ParentID int null)
insert into @t(ID,Name,ParentID) values
(1 ,'Alex',null),
(2 ,'John',null),
(3 ,'Don',1),
(4 ,'Philip',2),
(5 ,'Shiva',2),
(6 ,'San',3),
(7 ,'Antony',6),
(8 ,'Mathew',2),
(9 ,'Cyril',8),
(10,'Johan',9)

declare @search table (ID int not null)
insert into @search (ID) values (7),(10), (1);

;With Paths as (
    select s.ID as RootID,t.ID,t.ParentID,t.Name
     , CASE WHEN t.ParentId IS NULL THEN '-' 
            ELSE CONVERT(varchar(max),t.Name) END as Path
    from @search s
    join @t t
      on s.ID = t.ID
    union all
    select p.RootID,t.ID,t.ParentID,p.Name, t.Name + '->' + p.Path
    from Paths p
    join @t t
      on p.ParentID = t.ID
)
select *
from Paths 
where ParentID is null;

<强> Rextester Demo

Answer 2

根据您的架构和数据，此查询：

with P as
(
    select *, cast(null as nvarchar) as chain from People where parentID is null
        union all 
            select C.*, cast(coalesce(P.chain, P.name) + '->' + C.name as nvarchar) 
                from People C inner join P on C.parentID = P.id

)

select id, name, coalesce(chain, '-') relation from P where id in (7, 10, 1)

收率：

id    name    relation
----- ------  ------------------------------
1     Alex    -
10    Johan   John->Mathew->Cyril->Johan
7     Antony  Alex->Don->San->Antony

Rextester Demo

列出除最顶层节点之外的分隔字符串中的所有父级层次结构

2 个答案: