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重要...在我的 RL 项目中，ID 不是 INT，而是 GUID，所以我的数据不是分层的！

我有一张公司表和一张公司之间链接的表。

我需要能够从特定公司 ID 中检索公司列表。

这是我的测试代码...

CREATE TABLE ##corporations
(  
    CorporationID INT NOT NULL,  
    CorporationName NVARCHAR(20) NOT NULL
);  

CREATE TABLE ##corporationLinks
(  
    FromCorporationID INT NOT NULL,  
    ToCorporationID INT NOT NULL
);  

INSERT INTO ##corporations (CorporationID, CorporationName) VALUES (1, 'Nike')
INSERT INTO ##corporations (CorporationID, CorporationName) VALUES (2, 'Cocal Cola')
INSERT INTO ##corporations (CorporationID, CorporationName) VALUES (3, 'Apple')
INSERT INTO ##corporations (CorporationID, CorporationName) VALUES (4, 'Google')
INSERT INTO ##corporations (CorporationID, CorporationName) VALUES (5, 'Amazon')
INSERT INTO ##corporations (CorporationID, CorporationName) VALUES (6, 'Samsung')

INSERT INTO ##corporationLinks (FromCorporationID, ToCorporationID) VALUES (1, 2)
INSERT INTO ##corporationLinks (FromCorporationID, ToCorporationID) VALUES (2, 3)
INSERT INTO ##corporationLinks (FromCorporationID, ToCorporationID) VALUES (4, 5)
INSERT INTO ##corporationLinks (FromCorporationID, ToCorporationID) VALUES (4, 6)

SELECT * FROM ##corporationLinks WHERE FromCorporationID = 2 OR ToCorporationID = 2

/** 

Organisations (##corporationLinks) are...

Nike + Coca Cola + Apple + Marcy

and...

Google + Amazon + Samsung

**/

-- How do I eg get a list of companies where Coca Cola is in ... that is where FromCorporationID = 2 OR ToCorporationID = 2 ... result should be Nike, Coca Cola and Apple?
-- How do I eg get a list of companies where Samsung is in ... that is where FromCorporationID = 6 OR ToCorporationID = 6 ... result should be Google, Amazon Cola and Samsung?

DROP TABLE ##corporationLinks 
DROP TABLE ##corporations

UDPATE：

如果我需要找到可口可乐所在的公司，那么我会去寻找……

SELECT * FROM ##corporationLinks WHERE FromCorporationID = 2 或 ToCorporationID = 2

然后我会得到2个结果......

FromCorporationID   ToCorporationID
-----------------------------------
1                   2
2                   3

在此之后，我需要查看结果属于哪些公司...

SELECT * FROM ##corporationLinks WHERE FromCorporationID = 1 OR ToCorporationID = 1

SELECT * FROM ##corporationLinks WHERE FromCorporationID = 3 OR ToCorporationID = 3

然后我会再得到一个公司（7）：

FromCorporationID   ToCorporationID
-----------------------------------
3                   7

然后我需要深入了解与 7 相关的公司......

SELECT * FROM ##corporationLinks WHERE FromCorporationID = 7 OR ToCorporationID = 7

并深入研究该结果（猜想它被称为递归）。等等

更新 2：

我已经更新了上面的示例，添加了一个如果搜索是 Coca Cola 应该返回的公司。

上述查询（可口可乐）的预期结果：

CorporationID:
--------------
2
1
3
7
4

3 回答 3

0

只需使用递归 CTE

WITH cte
AS
(
    SELECT l1.FromCorporationID,l1.ToCorporationID
    FROM ##corporationLinks l1
    UNION ALL
    SELECT cte.FromCorporationID,l3.ToCorporationID
    FROM ##corporationLinks l3
    JOIN cte 
        ON cte.ToCorporationID = l3.FromCorporationID

)

SELECT cte.ToCorporationID--parent
FROM cte
WHERE cte.FromCorporationID =2
UNION
SELECT cte.FromCorporationID--child
FROM cte
WHERE cte.ToCorporationID =2
UNION
SELECT c.CorporationID--self
FROM ##corporations c
WHERE c.CorporationID = 2
于 2020-08-05T10:37:01.293 回答
0

使用递归CTE：

with 
  root as (select CorporationID id from companies where CorporationName = 'Coca Cola'),
  cte as (
    select 
      case when r.id = cl.FromCorporationID then cl.ToCorporationID else cl.FromCorporationID end id,
      case when r.id = cl.FromCorporationID then cl.FromCorporationID else cl.ToCorporationID end otherid      
    from corporationLinks cl inner join root r
    on r.id in (cl.FromCorporationID, cl.ToCorporationID)
    union all
    select 
      case when c.id = cl.FromCorporationID then cl.ToCorporationID else cl.FromCorporationID end id,
      case when c.id = cl.FromCorporationID then cl.FromCorporationID else cl.ToCorporationID end otherid            
    from corporationLinks cl inner join cte c
    on c.id in (cl.FromCorporationID, cl.ToCorporationID)
    and c.otherid not in (cl.FromCorporationID, cl.ToCorporationID)
  )
select id CorporationID from root
union all
select id from cte

请参阅演示。
结果：

> | CorporationID |
> | ------------: |
> |             2 |
> |             1 |
> |             3 |
> |             7 |
于 2020-08-05T10:30:39.493 回答
0

左加入##companies，包括其CorporationID，或者您可以在查询中包含公司名称，然后按CorporationID分组，您应该能够看到它属于哪个公司

于 2020-08-05T09:46:37.467 回答