如何在 sql 中使用 parent 和 child 层次结构 select 标题？

Question

我需要搜索标题 '%p%'。如果我检查标题，parent tile 和状态为 parent 和 child 级别。如果搜索到的标题 parent visible 为真，则显示 child 标题。

SELECT title
FROM table1 t1
JOIN table1 t2 ON t1.title = t2.parenttitle AND t1.visible = TRUE
JOIN table1 t3 ON t3.title = t2.parenttitle AND t3.visible = TRUE
WHERE t1.title LIKE '%p%'

表 1

Title   | ParentTitle|visible   
P1        Home         TRUE 
p1.1       p1          TRUE 
p1.2       p1          FALSE    
p1.3       p1.2        TRUE 
p1.3.1     p1.3        TRUE 
p2         Home        TRUE 
p2.1       p2          TRUE 
p2.2       p2.1        FALSE    
P3         Home        TRUE 
p3.1       p3          TRUE 
P3.1.1     p3.1        FALSE

我需要像

这样的输出

title
p1
p1.1
p2
p2.1
P3
p3.1

Answer 1

CREATE TABLE CTE(
    Title VARCHAR(20),
    ParentTitle VARCHAR(20),
    visible VARCHAR(20),    
)   

INSERT INTO CTE
VALUES
('p1', 'Home', 'TRUE'),
('p1.1', 'p1', 'TRUE'),
('p1.2', 'p1', 'FALSE'),    
('p1.3', 'p1.2', 'TRUE'), 
('p1.3.1', 'p1.3', 'TRUE'), 
('p2', 'Home', 'TRUE'), 
('p2.1', 'p2', 'TRUE'), 
('p2.2', 'p2.1', 'FALSE'),    
('P3', 'Home', 'TRUE'), 
('p3.1', 'p3', 'TRUE'), 
('P3.1.1', 'p3.1', 'FALSE')


; WITH YTE AS
(
    SELECT *,
    ROW_NUMBER() OVER(PARTITION BY LEFT(A.Title, 2) ORDER BY A.Title) AS RN,
    DENSE_RANK() OVER(ORDER BY LEFT(A.Title, 2)) AS DR
    FROM CTE A
)
, ZTE AS
(
    SELECT *, ROW_NUMBER() OVER(PARTITION BY LEFT(A.Title, 2) ORDER BY A.Title) AS RNFalse
    FROM YTE A 
    WHERE A.visible = 'FALSE'
)
, ATE AS 
(
    SELECT A.Title
    FROM YTE A
    INNER JOIN ZTE B ON A.DR = B.DR AND A.RN < B.RN
    WHERE RNFalse = 1
) SELECT * FROM ATE

/*
Output:
p1
p1.1
p2
p2.1
P3
p3.1
*/

如果不想使用普通的table表达式，那么使用子查询

SELECT A.Title FROM 
(
    SELECT *,
    ROW_NUMBER() OVER(PARTITION BY LEFT(A.Title, 2) ORDER BY A.Title) AS RN
    FROM CTE A
) AS A
INNER JOIN
(
    SELECT *,
    ROW_NUMBER() OVER(PARTITION BY LEFT(A.Title, 2) ORDER BY A.Title) AS RNFalse
    FROM 
    (
        SELECT *,
        ROW_NUMBER() OVER(PARTITION BY LEFT(A.Title, 2) ORDER BY A.Title) AS RN
        FROM CTE A
    ) A 
    WHERE A.visible = 'FALSE'
) AS B ON LEFT(A.Title, 2) = LEFT(B.Title, 2) AND A.RN < B.RN
WHERE B.RNFalse = 1

所以如果你想删除 ROW_NUMBER 那么你必须比较 varchar 这不好。但你没有别的办法留给我。试试这个，

SELECT A.Title FROM CTE A
INNER JOIN 
(
     SELECT LEFT(Title, 2) AS TitleGroup, Min(Title) AS Title
     FROM CTE
     WHERE visible = 'False'
     GROUP BY LEFT(Title, 2)
) B ON LEFT(A.Title, 2) = B.TitleGroup 
AND A.Title < B.Title --Comparing String like this is not good

如何在 sql 中使用 parent 和 child 层次结构 select 标题？

How to select title using parent and child hierarchy in sql?

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hierarchical-data