--\
---) Script: Generate new predictable GUIDs from existing ones - demo
---) Author: Hans Michiels
---) Website: www.hansmichiels.com
--/

--\
---) 1. Prepare for the demo
--/
USE [tempdb]
GO

IF OBJECT_ID('[dbo].[SalesOrderHeader]', 'U') IS NOT NULL
   DROP TABLE [dbo].[SalesOrderHeader];
IF OBJECT_ID('[dbo].[SalesOrderDetail]', 'U') IS NOT NULL
   DROP TABLE [dbo].[SalesOrderDetail];
GO

SELECT NEWID() AS [SalesOrderGUID], h.*
INTO [dbo].[SalesOrderHeader]
FROM [AdventureWorks].[Sales].[SalesOrderHeader] h

SELECT h.SalesOrderGUID, NEWID() AS [SalesOrderDetailGUID], d.*
INTO [dbo].[SalesOrderDetail]
FROM [AdventureWorks].[Sales].[SalesOrderDetail] d
JOIN [dbo].[SalesOrderHeader] h ON h.SalesOrderID = d.SalesOrderID

ALTER TABLE [tempdb].[dbo].[SalesOrderHeader] DROP COLUMN SalesOrderID;
ALTER TABLE [tempdb].[dbo].[SalesOrderDetail] DROP COLUMN SalesOrderID;
ALTER TABLE [tempdb].[dbo].[SalesOrderDetail] DROP COLUMN SalesOrderDetailID;
GO

--\
---) 2. Demonstrate how it works given the example that you would
---) want to copy an existing SalesOrder and its detail rows to
---) a new one, without having the dependency to insert the
---) header first, then retrieve the value for [SalesOrderGUID]
---) for the row, and then use it to insert the detail rows.
---) Using a new predictable unique identifier this lookup is
---) not needed.
--/

-- First we declare a value to use for 'Salt'. This makes sure that we could
-- copy the same source rows multiple times to new rows, because the generated
-- guids will be different every time the script runs.
-- We keep it simple and just use a timestamp as a salt value.
DECLARE @NewGuidSalt VARCHAR(30) = CONVERT(VARCHAR, GETDATE(), 120)
PRINT @NewGuidSalt

-- Again I keep the example very simple, hypothetical almost because the action
-- below is not likely for a real life example: we select 3 salesorders from a specific CustomerID and copy them to a different CustomerID.
-- However it explains the concept.
DECLARE @SourceCustomerID INT
DECLARE @TargetCustomerID INT

SELECT
  @SourceCustomerID = 11000
, @TargetCustomerID = 99999

-- Obviously it is important to run the entire operation
-- in a transaction and implement TRY CATCH to rollback
-- the transaction when an error occurs. For instance
-- a hash collision could occur (but the chance that it
-- happens is astronomically small).
BEGIN TRY

    BEGIN TRAN

    --\
    ---) 2a. Copy [SalesOrderHeader]
    --/
    INSERT INTO [dbo].[SalesOrderHeader]
      ( [SalesOrderGUID]
      , [RevisionNumber]
      , [OrderDate]
      , [DueDate]
      , [ShipDate]
      , [Status]
      , [OnlineOrderFlag]
      , [SalesOrderNumber]
      , [PurchaseOrderNumber]
      , [AccountNumber]
      , [CustomerID]
      , [SalesPersonID]
      , [TerritoryID]
      , [BillToAddressID]
      , [ShipToAddressID]
      , [ShipMethodID]
      , [CreditCardID]
      , [CreditCardApprovalCode]
      , [CurrencyRateID]
      , [SubTotal]
      , [TaxAmt]
      , [Freight]
      , [TotalDue]
      , [Comment]
      , [rowguid]
      , [ModifiedDate]
      )
    SELECT
        CONVERT(UNIQUEIDENTIFIER, HASHBYTES('MD5', CONVERT(CHAR(36), src.[SalesOrderGUID]) + @NewGuidSalt)) AS [SalesOrderGUID]
      , [RevisionNumber]
      , [OrderDate]
      , [DueDate]
      , [ShipDate]
      , [Status]
      , [OnlineOrderFlag]
      , [SalesOrderNumber]
      , [PurchaseOrderNumber]
      , [AccountNumber]
      , @TargetCustomerID AS [CustomerID]
      , [SalesPersonID]
      , [TerritoryID]
      , [BillToAddressID]
      , [ShipToAddressID]
      , [ShipMethodID]
      , [CreditCardID]
      , [CreditCardApprovalCode]
      , [CurrencyRateID]
      , [SubTotal]
      , [TaxAmt]
      , [Freight]
      , [TotalDue]
      , [Comment]
      , NEWID() AS [rowguid]
      , GETDATE() AS [ModifiedDate]
    FROM
        [dbo].[SalesOrderHeader] src
    WHERE
        src.CustomerID = @SourceCustomerID

    --\
    ---) 2b. Copy [SalesOrderDetail] rows
    --/
    INSERT INTO [dbo].[SalesOrderDetail]
      ( [SalesOrderGUID]
      , [SalesOrderDetailGUID]
      , [CarrierTrackingNumber]
      , [OrderQty]
      , [ProductID]
      , [SpecialOfferID]
      , [UnitPrice]
      , [UnitPriceDiscount]
      , [LineTotal]
      , [rowguid]
      , [ModifiedDate]
      )
    SELECT
        CONVERT(UNIQUEIDENTIFIER, HASHBYTES('MD5', CONVERT(CHAR(36), src.[SalesOrderGUID]) + @NewGuidSalt)) AS [SalesOrderGUID]
      , NEWID() AS [SalesOrderDetailGUID]
      -- For [SalesOrderDetailGUID] we simply use NEWID(), because it is not used somewhere else.
      , src.[CarrierTrackingNumber]
      , src.[OrderQty]
      , src.[ProductID]
      , src.[SpecialOfferID]
      , src.[UnitPrice]
      , src.[UnitPriceDiscount]
      , src.[LineTotal]
      , NEWID() AS [rowguid]
      , GETDATE() AS [ModifiedDate]
    FROM
        [dbo].[SalesOrderDetail] src
    JOIN
        [dbo].[SalesOrderHeader] h
        ON h.SalesOrderGUID = src.SalesOrderGUID
    WHERE
        h.CustomerID = @SourceCustomerID

    COMMIT TRAN;

END TRY
BEGIN CATCH
    IF @@TRANCOUNT > 0 ROLLBACK;
    DECLARE @ErrorMessage NVARCHAR(MAX) = ERROR_MESSAGE();
    RAISERROR(@ErrorMessage, 16, 1);
END CATCH

--\
---) 3. Now view the results
---) Note that the order detail rows are copied using the
---) same generated guid for [SalesOrderGUID]. Note that
---) if you would rerun the script starting with
---) “2. Demonstrate ..” you would get a second copy of the
---) same orders with orderdetails rows and with a different
---) generated guid for [SalesOrderGUID], due to the Salt
---) that was used.
--/
SELECT *
FROM
    [dbo].[SalesOrderHeader] h
WHERE
    h.CustomerID IN (@SourceCustomerID, @TargetCustomerID)

SELECT d.*
FROM
    [dbo].[SalesOrderDetail] d
JOIN
    [dbo].[SalesOrderHeader] h
    ON h.SalesOrderGUID = d.SalesOrderGUID
WHERE
    h.CustomerID IN (@SourceCustomerID, @TargetCustomerID)

GO

--\
---) 3. CLEANUP
--/
USE [tempdb]
GO

IF OBJECT_ID('[dbo].[SalesOrderHeader]', 'U') IS NOT NULL
   DROP TABLE [dbo].[SalesOrderHeader];
IF OBJECT_ID('[dbo].[SalesOrderDetail]', 'U') IS NOT NULL
   DROP TABLE [dbo].[SalesOrderDetail];
GO