これは、3つの関連するテーブルに簡単にスケーリングする方法です。
MERGEを使用してデータをコピーテーブルに挿入し、古いIDENTITY値と新しいIDENTITY値をコントロールテーブルに出力して、それらを関連テーブルのマッピングに使用できるようにします。
実際の答えは、2つのcreate tableステートメントと3つのマージだけです。残りはサンプルデータのセットアップと破棄です。
USE tempdb;
--## Create test tables ##--
CREATE TABLE Customers(
[Id] INT NOT NULL PRIMARY KEY IdENTITY,
[Name] NVARCHAR(200) NOT NULL
);
CREATE TABLE Orders(
[Id] INT NOT NULL PRIMARY KEY IdENTITY,
[CustomerId] INT NOT NULL,
[OrderDate] DATE NOT NULL,
CONSTRAINT [FK_Customers_Orders] FOREIGN KEY ([CustomerId]) REFERENCES [Customers]([Id])
);
CREATE TABLE OrderItems(
[Id] INT NOT NULL PRIMARY KEY IdENTITY,
[OrderId] INT NOT NULL,
[ItemId] INT NOT NULL,
CONSTRAINT [FK_Orders_OrderItems] FOREIGN KEY ([OrderId]) REFERENCES [Orders]([Id])
);
CREATE TABLE Customers2(
[Id] INT NOT NULL PRIMARY KEY IdENTITY,
[Name] NVARCHAR(200) NOT NULL
);
CREATE TABLE Orders2(
[Id] INT NOT NULL PRIMARY KEY IdENTITY,
[CustomerId] INT NOT NULL,
[OrderDate] DATE NOT NULL,
CONSTRAINT [FK_Customers2_Orders2] FOREIGN KEY ([CustomerId]) REFERENCES [Customers2]([Id])
);
CREATE TABLE OrderItems2(
[Id] INT NOT NULL PRIMARY KEY IdENTITY,
[OrderId] INT NOT NULL,
[ItemId] INT NOT NULL,
CONSTRAINT [FK_Orders2_OrderItems2] FOREIGN KEY ([OrderId]) REFERENCES [Orders2]([Id])
);
--== Populate some dummy data ==--
INSERT Customers(Name)
VALUES('Aaberg'),('Aalst'),('Aara'),('Aaren'),('Aarika'),('Aaron'),('Aaronson'),('Ab'),('Aba'),('Abad');
INSERT Orders(CustomerId, OrderDate)
SELECT Id, Id+GETDATE()
FROM Customers;
INSERT OrderItems(OrderId, ItemId)
SELECT Id, Id*1000
FROM Orders;
INSERT Customers2(Name)
VALUES('Zysk'),('Zwiebel'),('Zwick'),('Zweig'),('Zwart'),('Zuzana'),('Zusman'),('Zurn'),('Zurkow'),('ZurheIde');
INSERT Orders2(CustomerId, OrderDate)
SELECT Id, Id+GETDATE()+20
FROM Customers2;
INSERT OrderItems2(OrderId, ItemId)
SELECT Id, Id*1000+10000
FROM Orders2;
SELECT * FROM Customers JOIN Orders ON Orders.CustomerId = Customers.Id JOIN OrderItems ON OrderItems.OrderId = Orders.Id;
SELECT * FROM Customers2 JOIN Orders2 ON Orders2.CustomerId = Customers2.Id JOIN OrderItems2 ON OrderItems2.OrderId = Orders2.Id;
--== ** START ACTUAL ANSWER ** ==--
--== Create Linkage tables ==--
CREATE TABLE CustomerLinkage(old INT NOT NULL PRIMARY KEY, new INT NOT NULL);
CREATE TABLE OrderLinkage(old INT NOT NULL PRIMARY KEY, new INT NOT NULL);
--== Copy Header (Customers) rows and record the new key ==--
MERGE Customers2
USING Customers
ON 1=0 -- we just want an insert, so this forces every row as unmatched
WHEN NOT MATCHED THEN
INSERT (Name) VALUES(Customers.Name)
OUTPUT Customers.Id, INSERTED.Id INTO CustomerLinkage;
--== Copy Detail (Orders) rows using the new key from CustomerLinkage and record the new Order key ==--
MERGE Orders2
USING (SELECT Orders.Id, CustomerLinkage.new, Orders.OrderDate
FROM Orders
JOIN CustomerLinkage
ON CustomerLinkage.old = Orders.CustomerId) AS Orders
ON 1=0 -- we just want an insert, so this forces every row as unmatched
WHEN NOT MATCHED THEN
INSERT (CustomerId, OrderDate) VALUES(Orders.new, Orders.OrderDate)
OUTPUT Orders.Id, INSERTED.Id INTO OrderLinkage;
--== Copy Detail (OrderItems) rows using the new key from OrderLinkage ==--
MERGE OrderItems2
USING (SELECT OrderItems.Id, OrderLinkage.new, OrderItems.ItemId
FROM OrderItems
JOIN OrderLinkage
ON OrderLinkage.old = OrderItems.OrderId) AS OrderItems
ON 1=0 -- we just want an insert, so this forces every row as unmatched
WHEN NOT MATCHED THEN
INSERT (OrderId, ItemId) VALUES(OrderItems.new, OrderItems.ItemId);
--== ** END ACTUAL ANSWER ** ==--
--== Display the results ==--
SELECT * FROM Customers2 JOIN Orders2 ON Orders2.CustomerId = Customers2.Id JOIN OrderItems2 ON OrderItems2.OrderId = Orders2.Id;
--== Drop test tables ==--
DROP TABLE OrderItems;
DROP TABLE OrderItems2;
DROP TABLE Orders;
DROP TABLE Orders2;
DROP TABLE Customers;
DROP TABLE Customers2;
DROP TABLE CustomerLinkage;
DROP TABLE OrderLinkage;