ORACLE 遞歸獲取樹形結構數據

1.原始數據結構

2.使用關鍵字：CONNECT BY NOCYCLE

2.1.ERROR：ORA-01436，可使用關鍵字“ NOCYCLE”，自動跳過死循環代碼
2.2. SYS_CONNECT_BY_PATH， 可以得到完整的目錄樹
2.3. START WITH: 遞歸開始條件
2.4. CONNECT_BY_ROOT: 指定字段根節點的值

WITH V_ALL AS (
    SELECT 'A' AS CODE, 'A1' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'A' AS CODE, 'A2' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'A' AS CODE, 'B' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'B' AS CODE, 'B1' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'B' AS CODE, 'B2' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'B' AS CODE, 'C' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'C' AS CODE, 'D' AS ITEM_CODE FROM DUAL
)
SELECT
    CONNECT_BY_ROOT(A.CODE) AS CODE
    , A.ITEM_CODE
    , LEVEL AS NODE_INDEX
    , REPLACE('0' || SYS_CONNECT_BY_PATH(CODE, '>'), '>' || CODE, '') PARENT_TREE --  樹形目錄: 上一級層級
    , '0' || SYS_CONNECT_BY_PATH(CODE, '>') CURRENT_TREE  -- 樹形目錄: 當前層級
    , '0' || SYS_CONNECT_BY_PATH(CODE, '>') || '>' || A.ITEM_CODE AS CURRENT_NODE --  樹形目錄: 完整層級
FROM
    V_ALL A
--START WITH CODE = 'A'
CONNECT BY NOCYCLE A.CODE = PRIOR A.ITEM_CODE
ORDER BY CODE, CURRENT_NODE
;

2.5.結果

3.遞歸函數腳本

3.1.ERROR： ORA-32039: 遞歸 WITH 子句必須具有列別名列表
3.1.1.解決方法 - 臨時表后加上別名清單： RESULT(CODE, ITEM_CODE, NODE_INDEX, ROOT_CODE)

WITH V_ALL AS (
    SELECT 'A' AS CODE, 'A1' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'A' AS CODE, 'A2' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'A' AS CODE, 'B' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'B' AS CODE, 'B1' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'B' AS CODE, 'B2' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'B' AS CODE, 'C' AS ITEM_CODE FROM DUAL
    UNION ALL
    SELECT 'C' AS CODE, 'D' AS ITEM_CODE FROM DUAL
), V_G AS (
    SELECT CODE FROM V_ALL GROUP BY CODE
)
, RESULT(CODE, ITEM_CODE, NODE_INDEX, ROOT_CODE) as (
    SELECT V_G.CODE, V_ALL.ITEM_CODE AS ITEM_CODE, 1 AS NODE_INDEX , V_G.CODE AS ROOT_CODE
    FROM V_ALL
    INNER JOIN V_G ON V_G.CODE = V_ALL.CODE
    UNION ALL
    SELECT RESULT.CODE, V_ALL.ITEM_CODE, RESULT.NODE_INDEX + 1 AS NODE_INDEX, RESULT.ROOT_CODE
    FROM V_ALL
    INNER JOIN RESULT ON RESULT.ITEM_CODE = V_ALL.CODE
)
SELECT * FROM result
ORDER BY CODE, NODE_INDEX, ITEM_CODE

;

3.2.結果

 

Reference:

https://www.cnblogs.com/Soprano/p/10659127.html
https://blog.csdn.net/m0_46636892/article/details/122984132
https://blog.csdn.net/wang_yunj/article/details/51040029

 

connect by 用於存在父子，祖孫，上下級等層級關系的數據表進行層級查詢
oracle遞歸with
 https://oracle-base.com/articles/11g/recursive-subquery-factoring-11gr2