在SQL Server中复制对象层次结构的最佳方法是什么

Question

假设我们的层次结构由多个对象组成，如下所示：

我想复制这棵树（也许会以某种方式改变这些对象）。

执行此操作的一种简单方法是在对象之间进行迭代并逐个创建。但这里的表现很差。另外，我不喜欢循环; - ）

所以问题 - 是否可以使用基于集合的逻辑？

Answer 1

使用this question中描述的技术，您可以执行以下操作：

DECLARE @CartId int, @NewCartId int;
DECLARE @CartItems TABLE (OldId int, NewId int);

SET @CartId = ...;

INSERT INTO Shopping_Cart (
  Session_Id_Str,
  Name,
  Program_User_Id,
  Shopping_Cart_Status_Code,
  Placed_Order_Id)
SELECT
  Shopping_Cart_Id,
  Session_Id_Str,
  Name,
  Program_User_Id,
  Shopping_Cart_Status_Code,
  Placed_Order_Id
FROM Shopping_Cart
WHERE Shopping_Cart_Id = @CartId;
SET @NewCartId = SCOPE_IDENTITY();

WITH src AS (
  SELECT
    Shopping_Cart_Item_Id,
    @NewCartId AS Shopping_Cart_Id,
    Base_Product_Id,
    Product_Category_Id,
    Shop_Id,
    Currency_Code
  FROM Shopping_Cart_Item
  WHERE Shopping_Cart_Id = @CartId
)
MERGE Shopping_Cart_Item AS tgt
USING src
ON 0 = 1
WHEN NOT MATCHED THEN
  INSERT (
    Shopping_Cart_Id,
    Base_Product_Id,
    Product_Category_Id,
    Shop_Id,
    Currency_Code)
  VALUES (
    src.Shopping_Cart_Id,
    src.Base_Product_Id,
    src.Product_Category_Id,
    src.Shop_Id,
    src.Currency_Code)
OUTPUT
  src.Shopping_Cart_Item_Id,
  inserted.Shopping_Cart_Item_Id
INTO @CartItems (OldId, NewId);

WITH src AS (
  SELECT
    s.Shopping_Cart_Item_Detail_Id,
    map.NewId AS Shopping_Cart_Item_Id,
    s.Display_Order_Number,
    s.Product_Id,
    s.Product_Variant_Id
  FROM Shopping_Cart_Item_Detail s
    INNER JOIN @CartItems map ON s.Shopping_Cart_Item_Id = map.OldId
)
MERGE Shopping_Cart_Item_Detail AS tgt
USING src
ON 0 = 1
WHEN NOT MATCHED THEN
  INSERT (
    Shopping_Cart_Item_Id,
    Display_Order_Number,
    Product_Id,
    Product_Variant_Id)
  VALUES (
    src.Shopping_Cart_Item_Id,
    src.Display_Order_Number,
    src.Product_Id,
    src.Product_Variant_Id);

假设您只想一次复制一个“树”。

这一切都应该在一次交易中完成。