帶有共享成員的Oracle層次結構（雙父成員）

Question

我正在使用其中有一些具有雙父母或三父母的鍵的分層數據。

我必須編寫一個分層查詢來表示層次結構，但是這個雙重或三重父鍵必須單獨出現在樹中，顯示它們的子項只允許在三個中找到的第一個鍵中。

WITH HER(CHILD, PARENT) AS (
    SELECT 'A' AS CHILD, null AS PARENT FROM DUAL UNION 
    SELECT 'B' AS CHILD, 'A' AS PARENT FROM DUAL UNION 
    SELECT 'C' AS CHILD, 'A' AS PARENT FROM DUAL UNION 
    SELECT 'D' AS CHILD, 'C' AS PARENT FROM DUAL UNION 
    SELECT 'E' AS CHILD, 'D' AS PARENT FROM DUAL UNION 
    SELECT 'F' AS CHILD, null AS PARENT FROM DUAL UNION 
    SELECT 'G' AS CHILD, 'F' AS PARENT FROM DUAL UNION 
    SELECT 'C' AS CHILD, 'G' AS PARENT FROM DUAL UNION --<<--- shared 
    SELECT 'H' AS CHILD, null AS PARENT FROM DUAL UNION 
    SELECT 'B' AS CHILD, 'H' AS PARENT FROM DUAL UNION --<<--- shared 
    SELECT 'X' AS CHILD, null AS PARENT FROM DUAL UNION 
    SELECT 'Y' AS CHILD, 'X' AS PARENT FROM DUAL UNION 
    SELECT 'Z' AS CHILD, 'Y' AS PARENT FROM DUAL UNION 
    SELECT 'C' AS CHILD, 'Z' AS PARENT FROM DUAL  --<<--- shared 
    ) 
    SELECT 
     LPAD(' ', 7*(LEVEL-1),' ')||CHILD||' - '||PARENT 
    FROM HER 
    START WITH PARENT IS NULL 
    CONNECT BY PRIOR CHILD = PARENT 

;

從該查詢結果是這樣的，但它不是正是我試圖讓：

---------- 
A - 
     B - A 
     C - A 
       D - C 
        E - D 
F - 
     G - F 
       C - G 
        *D - C* 
          *E - D* 
H - 
     B - H 
X - 
     Y - X 
       Z - Y 
        C - Z 
          *D - C* 
            *E - D* 

行d-C和E-d應該只在「C」鍵的首次亮相被displayin。所以那些標有「*」的應該不會出現。

我知道我可以創建一個輔助查詢，在這個輔助查詢中我發現了這個雙親鍵，然後根據這個排除了行。 但是我不知道是否有最短的方法來做到這一點，與hiearchy本身一起工作....如果有一種方法可以知道一個密鑰已經有另一個父母。 （因爲這是一個視圖，我需要在查詢中這樣做，而不是PL/SQL。）

在此先感謝。

Answer 1

我承認我一般是sql-server，所以這是一個想法，但它可能需要一些調整和語法幫助。但是如何添加一個ROW_NUMBER（）在Child級別分區，並在connect by子句中添加第二個條件來限制遞歸。也許這樣？

WITH HER(CHILD, PARENT) AS (
    SELECT 'A' AS CHILD, null AS PARENT FROM DUAL UNION 
    SELECT 'B' AS CHILD, 'A' AS PARENT FROM DUAL UNION 
    SELECT 'C' AS CHILD, 'A' AS PARENT FROM DUAL UNION 
    SELECT 'D' AS CHILD, 'C' AS PARENT FROM DUAL UNION 
    SELECT 'E' AS CHILD, 'D' AS PARENT FROM DUAL UNION 
    SELECT 'F' AS CHILD, null AS PARENT FROM DUAL UNION 
    SELECT 'G' AS CHILD, 'F' AS PARENT FROM DUAL UNION 
    SELECT 'C' AS CHILD, 'G' AS PARENT FROM DUAL UNION --<<--- shared 
    SELECT 'H' AS CHILD, null AS PARENT FROM DUAL UNION 
    SELECT 'B' AS CHILD, 'H' AS PARENT FROM DUAL UNION --<<--- shared 
    SELECT 'X' AS CHILD, null AS PARENT FROM DUAL UNION 
    SELECT 'Y' AS CHILD, 'X' AS PARENT FROM DUAL UNION 
    SELECT 'Z' AS CHILD, 'Y' AS PARENT FROM DUAL UNION 
    SELECT 'C' AS CHILD, 'Z' AS PARENT FROM DUAL  --<<--- shared 
    ) 

    , HERChildRowNum(CHILD, PARENT, ChildRowNum) AS (

     SELECT 
      CHILD, 
      PARENT, 
      ROW_NUMBER() OVER (PARTITION BY CHILD ORDER BY (SELECT 0)) as ChildRowNum 
     FROM 
      HER 
    ) 


    SELECT 
     LPAD(' ', 7*(LEVEL-1),' ')||CHILD||' - '||PARENT 
    FROM HERChildRowNum 
    START WITH PARENT IS NULL 
    CONNECT BY PRIOR CHILD = PARENT AND (PRIOR ChildRowNum = ChildRowNum OR ChildRowNum>1)