的Oracle PL/SQL就根節點查詢

Question

早上好之前，

所以我有這樣的情況： 包含數據ID，parentdataID和一些信息

MyTable 
-Name 
-WorkingPeriod 
-ColorScheme 
-ID 
-parentID 

數據表來說明，表這樣的作品：

W0 (Always, Red) 
--W1 (First time, red-blue) 
----W2 (First step, red-blue-grey) 
----W3 (Second step, red-blue-black) 
------W4 (...) 
--------W5 (...) 
--W6 (Second time, red-green) 
----W7 (First step, red-green-grey) 
--W8 (Third time, red-pink) 

我需要，爲每種情況，以獲得最接近的根節點。這意味着：

• 爲W3，W4和W5，我想W1信息（第一次，紅 - 藍）
• 爲W1，我想沒有什麼（或者它自己的信息，可以與工作）
• 對於W0，我什麼都不需要。

希望我能說清楚自己。 祝您有美好的一天。

Answer 1

有了充分肯定Pablomatico爲起點，看看這個擴張他的工作是包括對不是2位數字的ID處理，並重新加入到源帶回剛剛纔根排的屬性：

WITH the_table AS (SELECT 'W0' item_id, NULL parent_id, 'Red' colour FROM DUAL 
        UNION 
        SELECT 'W1' item_id, 'W0' parent_id , 'blue' colour FROM DUAL 
        UNION 
        SELECT 'W2' item_id, 'W1' parent_id, 'Grey' colour FROM DUAL 
        UNION 
        SELECT 'W3' item_id, 'W1' parent_id, 'Black' colour FROM DUAL 
        UNION 
        SELECT 'W4' item_id, 'W3' parent_id, 'Mauve' colour FROM DUAL 
        UNION 
        SELECT 'W5' item_id, 'W4' parent_id, 'Orange' colour FROM DUAL 
        UNION 
        SELECT 'W6' item_id, 'W0' parent_id, 'Green' colour FROM DUAL 
        UNION 
        SELECT 'W7' item_id, 'W6' parent_id, 'Grey' colour FROM DUAL 
        UNION 
        SELECT 'W8' item_id, 'W0' parent_id, 'Pink' colour FROM DUAL) 
SELECT main_tab.item_id, main_tab.colour,main_tab.just_before_root, the_Table.colour 
FROM      
(SELECT item_id, 
     colour, 
     SYS_CONNECT_BY_PATH(item_id, '/') node_path, 
     CASE WHEN INSTR(SYS_CONNECT_BY_PATH(item_id, '/'),'/',1,2) = 0 THEN NULL 
      WHEN INSTR(SYS_CONNECT_BY_PATH(item_id, '/'),'/',1,2) != 0 
       AND INSTR(SYS_CONNECT_BY_PATH(item_id, '/'),'/',1,3) = 0 
       THEN SUBSTR(SYS_CONNECT_BY_PATH(item_id, '/'), INSTR(SYS_CONNECT_BY_PATH(item_id, '/'),'/',1,2)+1) 
      ELSE SUBSTR(SYS_CONNECT_BY_PATH(item_id, '/'), INSTR(SYS_CONNECT_BY_PATH(item_id, '/'),'/',1,2)+1,INSTR(SYS_CONNECT_BY_PATH(item_id, '/'),'/',1,3) - INSTR(SYS_CONNECT_BY_PATH(item_id, '/'),'/',1,2) - 1) END just_before_root 
FROM the_table 
CONNECT BY PRIOR item_id = parent_id 
START WITH parent_id IS NULL) main_tab 
left outer join the_table on main_tab.just_before_root = the_table.item_id; 

返回：

ITEM_ID COLOUR JUST_BEFORE_ROOT COLOUR_1 
"W0"  "Red"       
"W1"  "blue" "W1"    "blue"  
"W2"  "Grey" "W1"    "blue"  
"W3"  "Black" "W1"    "blue"  
"W4"  "Mauve" "W1"    "blue"  
"W5"  "Orange" "W1"    "blue"  
"W6"  "Green" "W6"    "Green"  
"W7"  "Grey" "W6"    "Green"  
"W8"  "Pink" "W8"    "Pink"  

Answer 2

create or replace function getNodeCloserToRoot 
(
    p_given_node varchar2(50); 
) 
return varchar2 
is 
v_parent_node varchar2(50); 
v_current_node varchar2(50) := p_given_node; 
begin 
    select parentDataId 
    into v_parent_node 
    from MyTable 
    where dataId = v_current_node; 
    loop 
    exit when v_parent_node is null; 
     v_current_node := v_parent_node; 
     select parentDataId 
     into v_parent_node 
     from MyTable 
     where dataId = v_current_node; 
    end loop; 

    return v_current_node; 
end; 

Answer 3

如前所述，您可以通過分層查詢來完成它。您可以構建每個節點的路徑並從該字符串的根之前提取節點。像這樣的東西可以幫助你得到最終的解決方案：

WITH the_table AS (SELECT 'W0' item_id, NULL parent_id FROM DUAL 
        UNION 
        SELECT 'W1' item_id, 'W0' parent_id FROM DUAL 
        UNION 
        SELECT 'W2' item_id, 'W1' parent_id FROM DUAL 
        UNION 
        SELECT 'W3' item_id, 'W1' parent_id_idrent FROM DUAL 
        UNION 
        SELECT 'W4' item_id, 'W3' parent_id FROM DUAL 
        UNION 
        SELECT 'W5' item_id, 'W4' parent_id FROM DUAL 
        UNION 
        SELECT 'W6' item_id, 'W0' parent_id FROM DUAL 
        UNION 
        SELECT 'W7' item_id, 'W6' parent_id FROM DUAL 
        UNION 
        SELECT 'W8' item_id, 'W0' parent_id FROM DUAL) 
SELECT item_id, 
     SYS_CONNECT_BY_PATH(item_id, '/') node_path, 
     SUBSTR(SYS_CONNECT_BY_PATH(item_id, '/'), 5, 2) just_before_root 
FROM the_table 
CONNECT BY PRIOR item_id = parent_id 
START WITH parent_id IS NULL;