sql server圖查詢，找到所有節點的路徑

Question

我有一個非常常見的問題，我試圖使用圖形查詢（sql server 2017）來解決。

1. 我想構建一個查詢並找出節點中的任何人如何連接到C 。
2. 我想構建一個查詢並找出節點中的任何人如何連接到C （具有 1 或 2 個連接）。

這是創建此圖的完整腳本：

DROP TABLE IF EXISTS Person;
CREATE TABLE Person (userName VARCHAR(100)  PRIMARY KEY) AS NODE;

INSERT INTO Person (userName) VALUES ('A'),('B'),('C'),('D'),('E'),('F'); 

DROP TABLE IF EXISTS Follow; 
CREATE TABLE Follow AS EDGE;

INSERT INTO Follow ($from_id, $to_id) VALUES (
   (SELECT $node_id FROM dbo.Person WHERE userName = 'A'),
   (SELECT $node_id FROM dbo.Person WHERE userName = 'E')),

   ((SELECT $node_id FROM dbo.Person WHERE userName = 'E'),
   (SELECT $node_id FROM dbo.Person WHERE userName = 'C')),


   ((SELECT $node_id FROM dbo.Person WHERE userName = 'C'),
   (SELECT $node_id FROM dbo.Person WHERE userName = 'A')),


   ((SELECT $node_id FROM dbo.Person WHERE userName = 'A'),
   (SELECT $node_id FROM dbo.Person WHERE userName = 'F')),

   ((SELECT $node_id FROM dbo.Person WHERE userName = 'F'),
   (SELECT $node_id FROM dbo.Person WHERE userName = 'B')),

   ((SELECT $node_id FROM dbo.Person WHERE userName = 'B'),
   (SELECT $node_id FROM dbo.Person WHERE userName = 'F')),

   ((SELECT $node_id FROM dbo.Person WHERE userName = 'B'),
   (SELECT $node_id FROM dbo.Person WHERE userName = 'E')),

   ((SELECT $node_id FROM dbo.Person WHERE userName = 'E'),
   (SELECT $node_id FROM dbo.Person WHERE userName = 'B'));

這個查詢不起作用，因為它只給我直接關系：

SELECT Person1.userName as userName1, Person2.userName as userName2   
FROM Person as Person1, Follow, Person as Person2 
WHERE MATCH(Person1-(Follow)->Person2)
AND Person2.userName = 'C'

Answer 1

您可以嘗試以下操作：

SELECT 
        p1.userName, 
        p1.userName as StartNode,
        LAST_VALUE(p2.userName) WITHIN GROUP (GRAPH PATH) AS FinalNode,
        STRING_AGG(p2.userName,'->') WITHIN GROUP (GRAPH PATH) AS [Edges Path],
        COUNT(p2.userName) WITHIN GROUP (GRAPH PATH) AS Levels
    FROM
        dbo.Person p1,
        dbo.Person FOR PATH p2,
        dbo.Follow FOR PATH Follow
    WHERE 
        MATCH(SHORTEST_PATH(p1(-(Follow)->p2)+))
        AND p1.userName = 'C';

要查找節點的所有傳入連接，我們需要為最終節點包裝查詢和過濾器，如下所示：

SELECT
    username, StartNode, [Edges Path], FinalNode, Levels
FROM (
    SELECT 
        P1.username, 
        P1.username as StartNode, 
        STRING_AGG(P2.userName,'->') WITHIN GROUP (GRAPH PATH) AS [Edges Path],
        LAST_VALUE(P2.userName) WITHIN GROUP (GRAPH PATH) AS FinalNode,
        COUNT(P2.userName) WITHIN GROUP (GRAPH PATH) AS Levels
    FROM
        Person P1,
        Person FOR PATH P2,
        Follow FOR PATH Follow
    WHERE 
        MATCH(SHORTEST_PATH(P1(-(Follow)->P2)))
 ) AS Q
 WHERE Q.FinalNode = 'C'

為了限制跳躍的級別或數量，我們可以提供遞歸量詞來代替 (+ --- 一個或多個)，如下所示：

SELECT
    username, StartNode, [Edges Path], FinalNode, Levels
FROM (
    SELECT 
        P1.username, 
        P1.username as StartNode, 
        STRING_AGG(P2.userName,'->') WITHIN GROUP (GRAPH PATH) AS [Edges Path],
        LAST_VALUE(P2.userName) WITHIN GROUP (GRAPH PATH) AS FinalNode,
        COUNT(P2.userName) WITHIN GROUP (GRAPH PATH) AS Levels
    FROM
        Person P1,
        Person FOR PATH P2,
        Follow FOR PATH Follow
    WHERE 
        MATCH(SHORTEST_PATH(P1(-(Follow)->P2){1,3}))
 ) AS Q
 WHERE Q.FinalNode = 'C'