Consolidation of two data rows in a loop for n occurrences - sql-server

Question

We are running a table that holds some information for order of new products.
From time to time we receive new orders from a 3rd party system and insert them into our DB.
Sometimes, however, for a specific order there is already an entry in our table.
So instead of checking if there already IS an order, the colleagues just inserts new data sets into our table.
Now that the process of inserting is streamlined, I am supposed to consolidate the existing duplicates in the table.
The table looks like this:
I have 138 of these pairs where the PreOrderNumber occurrs twice. I'd like to insert the FK_VehicleFile number and the CommissionNumber to the row where the FK_Checklist is set and delete the duplicate with the missing FK_Checklist after that.
My idea is to write a transact script that looks like this:
First I store all the PreOrderNumbers that have duplicates in its an own table:
DECLARE #ResultSet TABLE ( PK_OrderNumber int,
FK_Checklist int,
FK_VehicleFile int,
PreOrderNumbers varchar(20))
INSERT INTO #ResultSet
SELECT PK_OrderNumber, PreOrderNumber
FROM [LUX_WEB_SAM].[dbo].[OrderNumbers]
GROUP BY PreOrderNumber
HAVING (COUNT(PreOrderNumber) > 1)
And that's it so far.
I'm very new to these kind of SQL scripts.
I think I need to use some kind of loop over all entries in the #ResultSet table to grab the FK_VehicleFile and CommissionNumber from the first data set and store them in the second data set.
Or do you have and suggestions how to solve this problem in a more easy way?

Answer 1

This response uses a CTE:
WITH [MergedOrders] AS
(
Select
ROW_NUMBER() OVER(PARTITION BY row1.PreOrderNumber ORDER BY row1.PK_OrderNumber) AS Instance
,row1.PK_OrderNumber AS PK_OrderNumber
,ISNULL(row1.FK_Checklist,row2.FK_Checklist) AS FK_Checklist
,ISNULL(row1.FK_VehicleFile,row2.FK_VehicleFile) AS FK_VehicleFile
,ISNULL(row1.PreOrderNumber,row2.PreOrderNumber) AS PreOrderNumber
,ISNULL(row1.CommissionNumber,row2.CommissionNumber) AS CommissionNumber
FROM [LUX_WEB_SAM].[dbo].[OrderNumbers] AS row1
INNER JOIN [LUX_WEB_SAM].[dbo].[OrderNumbers] AS row2
ON row1.PreOrderNumber = row2.PreOrderNumber
AND row1.PK_OrderNumber <> row2.PK_OrderNumber
)
SELECT
[PK_OrderNumber]
,[FK_Checklist]
,[FK_VehicleFile]
,[PreOrderNumber]
,[CommissionNumber]
FROM [MergedOrders]
WHERE Instance = 1 /* If we were to maintain Order Number of second instance, use 2 */
Here's the explanation:
A Common Table Expression (CTE) acts as an in-memory table, which we use to extract all rows that are repeated (NB: The INNER JOIN statement ensures that only rows that occur twice are selected). We use ISNULL to switch out values where one or the other is NULL, then select the output for our destination table.

Answer 2

You can take help from following scripts to perform your UPDATE and DELETE action.
Please keep in mind that both UPDATE and DELETE are risky operation and do your test first with test data.
CREATE TABLE #T(
Col1 VARCHAR(100),
Col2 VARCHAR(100),
Col3 VARCHAR(100),
Col4 VARCHAR(100),
Col5 VARCHAR(100)
)
INSERT INTO #T(Col1,Col2,Col3,Col4,Col5)
VALUES(30,NULL,222,00000002222,096),
(25,163,NULL,00000002222,NULL),
(30,163,NULL,00000002230,NULL)
SELECT * FROM #T
UPDATE A
SET A.Col3 = B.Col3, A.Col5 = B.Col5
FROM #T A
INNER JOIN #T B ON A.Col4 = B.Col4
WHERE A.Col2 IS NOT NULL AND B.Col2 IS NULL
DELETE FROM #T
WHERE Col4 IN (
SELECT Col4 FROM #T
GROUP BY Col4
HAVING COUNT(*) = 2
)
AND Col2 IS NULL
SELECT * FROM #T