使用SQL克隆數據庫中

Question

代表的樹形結構鑑於代表樹狀層次結構有三列

1. ID表（主鍵，未自增）
2. ParentGroupID
3. someValue中

我知道該分支的最低節點，我想將它複製到具有相同數量父母的新分支，這些分支也需要克隆。

我正在嘗試編寫一個SQL INSERT INTO語句，該語句將使每個具有相同主體的行的副本具有第一部分GroupID到新的GroupID中。

實例開始表：

ID | ParentGroupID | SomeValue 
------------------------ 
1 |  -1  | a 
2 |  1  | b 
3 |  2  | c 

目標我運行一個簡單的INSERT INTO語句後：

ID | ParentGroupID | SomeValue 
------------------------ 
1 |  -1  | a 
2 |  1  | b 
3 |  2  | c 
4 |  -1  | a-cloned 
5 |  4  | b-cloned 
6 |  5  | c-cloned 

最終的樹結構

+--a (1) 
| +--b (2) 
|  +--c (3) 
| 
+--a-cloned (4) 
| +--b-cloned (5) 
|  +--c-cloned (6) 

ID是不總是很好地隔開因爲這個演示數據顯示，所以我不能總是假定父母的ID比1小1具有父母的行的當前ID。

此外，我正在嘗試在T-SQL（對於Microsoft SQL Server 2005及更高版本）中執行此操作。

這聽起來像一個經典的練習，應該有一個純SQL答案，但我太習慣編程了，我的思想在關係型SQL中並不認爲。

Answer 1

試試這個，根據從查詢Quassnoi的文章Adjacency List vs Nested Sets: SQL Server：

WITH q AS 
(
    SELECT h.*, 1 AS level 
    FROM Table1 h 
    WHERE id = 3 
    UNION ALL 
    SELECT hp.*, level + 1 
    FROM q 
    JOIN Table1 hp 
    ON  hp.id = q.ParentGroupID 
), q2 AS (
    SELECT 
     ID, 
     ParentGroupID, 
     SomeValue, 
     (SELECT MAX(level) FROM q) - level AS level 
    FROM q 
) 
INSERT INTO table1 
SELECT 
    (SELECT MAX(ID) FROM Table1) + level + 1 AS ID, 
    CASE WHEN level = 0 THEN -1 
     ELSE (SELECT MAX(ID) FROM Table1) + level 
    END AS ParentGroupID, 
    SomeValue + '-cloned' 
FROM q2 

結果，當您的測試數據上運行：

ID ParentGroupID SomeValue 
1 -1    a   
2 1    b   
3 2    c   
4 -1    a-cloned 
5 4    b-cloned 
6 5    c-cloned 

Answer 2

Assming該ID是標識列，具有自動分配的值。 我正在做這個袖口，所以任何語法錯誤appologies。我希望評論意圖清楚。

/* Find all ancestors for a given ID */ 
WITH Ancestors(ChildID, AncestorID) AS 
(
    SELECT id AS ChildID, id As AncestorID 
    FROM YourTable WHERE ParentGroupID=--1 
    UNION ALL 
    SELECT a.ChildID, d.ParentGroupID 
    FROM Ancestors AS a INNER JOIN 
     YourTable d ON d.ID = a.AncestorID 
    WHERE (b1.ParentGroupID <> -1)) 
), 
/* Insert new rows for all ancestors of a given ID and save the results, so we have access to the new ID. we also have a column for the old ID. */ 
IDMap(ID, ParentGroupID, SomeValue, OldID) AS 
{ 
    // insert, using identity column assigned ID, and save the old ID 
    INSERT INTO YourTable SELECT d.ParentGroupID, d.SomeValue+"-cloned", d.ID FROM YourTable d 
     INNER JOIN Ancestors a ON a.ChildID = d.ID 
     WHERE a.AncestorID=<the ID to clone> 
} 
/* Now update the parentID in the inserted data to the new ID */ 
UPDATE YourTable 
SET ParentGroupID = map.ID 
FROM YouTable t INNER JOIN (SELECT * FROM IDMap) map 
    ON t.ParentGroupID=map.OldID