SQLSERVER 递归查询

CREATE TABLE #temp_knowledge
    (
      knowledge_name NVARCHAR(MAX) ,
      knowledge_id INT ,
      p_knowledge_id INT
    );
    
    
INSERT  INTO #temp_knowledge
        ( knowledge_name ,
          knowledge_id ,
          p_knowledge_id
        )
VALUES  ( N'知识点1' , -- knowledge_name - nvarchar(max)
          1 , -- knowledge_id - int
          0  -- p_knowledge_id - int
        );
INSERT  INTO #temp_knowledge
        ( knowledge_name ,
          knowledge_id ,
          p_knowledge_id
        )
VALUES  ( N'知识点1.1' , -- knowledge_name - nvarchar(max)
          2 , -- knowledge_id - int
          1  -- p_knowledge_id - int
        );
INSERT  INTO #temp_knowledge
        ( knowledge_name ,
          knowledge_id ,
          p_knowledge_id
        )
VALUES  ( N'知识点1.2' , -- knowledge_name - nvarchar(max)
          3 , -- knowledge_id - int
          1  -- p_knowledge_id - int
        );
    
INSERT  INTO #temp_knowledge
        ( knowledge_name ,
          knowledge_id ,
          p_knowledge_id
        )
VALUES  ( N'知识点1.3' , -- knowledge_name - nvarchar(max)
          4 , -- knowledge_id - int
          1  -- p_knowledge_id - int
        );
    
INSERT  INTO #temp_knowledge
        ( knowledge_name ,
          knowledge_id ,
          p_knowledge_id
        )
VALUES  ( N'知识点1.1.1' , -- knowledge_name - nvarchar(max)
          5 , -- knowledge_id - int
          2  -- p_knowledge_id - int
        );
    
INSERT  INTO #temp_knowledge
        ( knowledge_name ,
          knowledge_id ,
          p_knowledge_id
        )
VALUES  ( N'知识点1.1.2' , -- knowledge_name - nvarchar(max)
          6 , -- knowledge_id - int
          2  -- p_knowledge_id - int
        );
INSERT  INTO #temp_knowledge
        ( knowledge_name ,
          knowledge_id ,
          p_knowledge_id
        )
VALUES  ( N'知识点2' , -- knowledge_name - nvarchar(max)
          7 , -- knowledge_id - int
          0  -- p_knowledge_id - int
        );
INSERT  INTO #temp_knowledge
        ( knowledge_name ,
          knowledge_id ,
          p_knowledge_id
        )
VALUES  ( N'知识点2.1' , -- knowledge_name - nvarchar(max)
          8 , -- knowledge_id - int
          7  -- p_knowledge_id - int
        );
        
INSERT  INTO #temp_knowledge
        ( knowledge_name ,
          knowledge_id ,
          p_knowledge_id
        )
VALUES  ( N'知识点2.2' , -- knowledge_name - nvarchar(max)
          9 , -- knowledge_id - int
          7  -- p_knowledge_id - int
        );
        
      
--查询该知识点id下的所以集合
DECLARE @knowledge_id INT = 1;   

WITH    data
          AS ( SELECT   *
               FROM     #temp_knowledge tk
               WHERE    knowledge_id = @knowledge_id
               UNION ALL
               SELECT   tk.*
               FROM     #temp_knowledge tk
                        INNER JOIN data d ON tk.p_knowledge_id = d.knowledge_id
             )
    SELECT  *
    FROM    data;

DROP TABLE #temp_knowledge;

所有知识点集合：

SELECT * FROM #temp_knowledge

 递归查询知识点id等于1下的所有子集：

--查询该知识点id下的所以集合
DECLARE @knowledge_id INT = 1;   

WITH    data
          AS ( SELECT   *
               FROM     #temp_knowledge tk
               WHERE    knowledge_id = @knowledge_id
               UNION ALL
               SELECT   tk.*
               FROM     #temp_knowledge tk
                        INNER JOIN data d ON tk.p_knowledge_id = d.knowledge_id
             )
    SELECT  *
    FROM    data;