Duplicates pointing to ID - SQL Server Forums

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Duplicates pointing to ID

Author

Topic

ben_53
Yak Posting Veteran

67 Posts

Posted - 2011-09-09 : 18:47:16

Hi guys,
I have a tableA

ID col1 col2 status
1 ABC 123 NULL
2 ABC 214 NULL
3 BCA 001 NULL
4 ABC 123 NULL
5 BWE 765 NULL
6 ABC 123 NULL
7 BCA 001 NULL

I want to flag the duplicate data (col1, col2) & populate the column=status with a message referring to the ID of which is duplicate.
For example, ID=4 is duplicate of ID = 1 , ID=6 is duplicate of ID = 1 and ID 7 is duplicate of ID = 3.
status = "Duplicate of ID = (ID here) "
Expected result:

ID col1 col2 status
1 ABC 123 NULL
2 ABC 214 NULL
3 BCA 001 NULL
4 ABC 123 Duplicate of ID = 1
5 BWE 765 NULL
6 ABC 123 Duplicate of ID = 1
7 BCA 001 Duplicate of ID = 3

I can able to flag the duplicates but cant able to point then to the ID numbers. The script I used is :

WITH CTE_Duplicates1 AS
(SELECT ROW_NUMBER() OVER (PARTITION BY col1,col2
ORDER BY (SELECT 0)) RN,Status
FROM tableA
)
UPDATE CTE_Duplicates1
SET qnxtStatus = 'Duplicate of ID ='
WHERE RN<>1

Please correct. Thanks

ben_53
Yak Posting Veteran

67 Posts

Posted - 2011-09-09 : 20:07:27

Solution :

;WITH CTE_Duplicates1 AS
(
SELECT MIN(ID) OVER (PARTITION BY col1, col2) Mn,
ROW_NUMBER() OVER (PARTITION BY col1, col2 ORDER BY $/0) Rn,
*
FROM tableA
)
UPDATE CTE_Duplicates1
SET qnxtStatus = 'Duplicate of ID =' + CAST(Mn AS VARCHAR(11))
WHERE Rn > 1

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