SQL Dynamically update duplicate row values to be unique - sql

Question

The Problem
I need to update a table so that any duplicate rows are updated to have unique values.
The Catch
I need to dynamically ensure that the value I am updating the duplicate row to is also unique.
My Solution So Far (with test case)
CREATE TABLE #temp (name nvarchar(100), ID uniqueidentifier)
INSERT INTO #temp (Name, ID)
VALUES ('Duplicate', '32208C09-C0C3-408C-AB60-273811722194')
INSERT INTO #temp (Name, ID)
VALUES ('Duplicate', '32208C09-C0C3-408C-AB60-273811722194')
INSERT INTO #temp (Name, ID)
VALUES ('Duplicate (2)', '32208C09-C0C3-408C-AB60-273811722194')
;WITH cte AS (
SELECT Name
, ROW_NUMBER() OVER (PARTITION BY Name, ID ORDER BY Name) RowNum
FROM #temp
)
UPDATE cte
SET Name = CONCAT(Name, ' (', RowNum, ')')
WHERE RowNum > 1
SELECT * FROM #temp
DROP TABLE #temp
As you can tell, this will update the table so there is only one row with the name 'Duplicate' but two rows with the name 'Duplicate (2)'. How can I check and account for duplicates in the value I am updating to?

Answer 1

You could use another CTe which gets you the highest Number and then use that to generate the "next" number.
for 2 or more digits you need to adapt it
CREATE TABLE #temp (name nvarchar(100), AssetMakeID uniqueidentifier)
INSERT INTO #temp (Name, AssetMakeID)
VALUES ('Duplicate', '32208C09-C0C3-408C-AB60-273811722194')
INSERT INTO #temp (Name, AssetMakeID)
VALUES ('Duplicate', '32208C09-C0C3-408C-AB60-273811722194')
INSERT INTO #temp (Name, AssetMakeID)
VALUES ('Duplicate (2)', '32208C09-C0C3-408C-AB60-273811722194')
;WITH CTE1 AS (SELECT
MAX( COALESCE(REPLACE(REPLACE(SUBSTRING(name, PATINDEX('%([0-9])%', name), PATINDEX('%)%', name + 't') - PATINDEX('%(%',
name) + 1),'(','') ,')','') ,0)) hinum
,SUBSTRING(name,1, PATINDEX('% ([0-9])%', name) ) name
FROM #temp
WHERE SUBSTRING(name,1, PATINDEX('% ([0-9])%', name) ) IS NOT NULL
GROUP BY SUBSTRING(name,1, PATINDEX('% ([0-9])%', name) ) ),
cte AS (
SELECT #temp.Name
, CASE WHEN ROW_NUMBER() OVER (PARTITION BY #temp.Name, AssetMakeID ORDER BY #temp.Name) > 1 THEN
ROW_NUMBER() OVER (PARTITION BY #temp.Name, AssetMakeID ORDER BY #temp.Name) + hinum -1
ELSe ROW_NUMBER() OVER (PARTITION BY #temp.Name, AssetMakeID ORDER BY #temp.Name) END RowNum
FROM #temp LEFT JOIN CTE1 ON #temp.name = CTE1.name
)
UPDATE cte
SET Name = CONCAT(Name, ' (', RowNum, ')')
WHERE RowNum > 1
SELECT * FROM #temp
name
AssetMakeID
Duplicate
32208c09-c0c3-408c-ab60-273811722194
Duplicate (3)
32208c09-c0c3-408c-ab60-273811722194
Duplicate (2)
32208c09-c0c3-408c-ab60-273811722194
fiddle

Answer 2

Well the easy way is to use a unique string in the update so there is no way your update can cause a duplicate. The current timestamp (with milliseconds) works well. Like this:
UPDATE cte
SET Name = CONCAT(Name, ' (', RowNum, ') at ',convert(varchar(22),getdate(),126))
WHERE RowNum > 1

Answer 3

This will cope with one level of duplication e.g. 'Duplicate (2)' but not two e.g. 'Duplicate (2) (2)'.
Essentially just apply the same logic again in a second cte. In fact you should be able to do this using a recursive CTE to get it to work for all levels.
That said you could use a more unique method of de-duplicating names e.g. just add a guid and it will be unique.
WITH cte1 AS (
SELECT Name, Id
, ROW_NUMBER() OVER (PARTITION BY Name, ID ORDER BY Name) RowNum
-- You should already have one, but if not generate it
, ROW_NUMBER() OVER (ORDER BY Name) UniqueId
FROM #temp
), cte2 as (
SELECT NewName Name, RowNum, UniqueId
, ROW_NUMBER() OVER (PARTITION BY NewName, ID ORDER BY NewName) RowNum2
FROM cte1
CROSS APPLY (
VALUES (CASE WHEN RowNum = 1 THEN Name ELSE CONCAT(Name, ' (', RowNum, ')') END)
) n (NewName)
)
UPDATE c1 SET
Name = CASE WHEN RowNum2 = 1 THEN c2.Name ELSE CONCAT(c2.Name, ' (', RowNum2, ')') END
FROM cte1 c1
INNER JOIN cte2 c2 on c2.UniqueId = c1.UniqueId
WHERE c1.RowNum > 1 or RowNum2 > 1;

Answer 4

I am going to choose another answer as the correct answer since I personally prefer it, but I thought I'd post what I ended up doing myself.
DROP TABLE IF EXISTS #temp
CREATE TABLE #temp (name nvarchar(100), ID uniqueidentifier)
INSERT INTO #temp (Name, ID)
VALUES ('Duplicate', '32208C09-C0C3-408C-AB60-273811722194')
INSERT INTO #temp (Name, ID)
VALUES ('Duplicate', '32208C09-C0C3-408C-AB60-273811722194')
INSERT INTO #temp (Name, ID)
VALUES ('Duplicate (2)', '32208C09-C0C3-408C-AB60-273811722194')
DECLARE #doWhileTrueFlag bit = 1
WHILE (#doWhileTrueFlag = 1)
BEGIN
;WITH cte AS (
SELECT
Name,
ROW_NUMBER() OVER (PARTITION BY Name, ID ORDER BY Name) RowNum
FROM #temp
)
UPDATE cte
SET Name = CONCAT(Name, ' (', RowNum, ')')
WHERE RowNum > 1
SET #doWhileTrueFlag = CASE
WHEN ##ROWCOUNT > 0 THEN 1
ELSE 0
END
END
SELECT * FROM #temp
DROP TABLE #temp
This performs the update I was already doing in a loop until no more updates are done. A rather inelegant solution, but the names created are prettier for the clients.