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How to remove duplicate records in SQL Server table with Primary Key and without primary key?

Posted on 2009-07-13
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Last Modified: 2012-08-14
I found many link to remove duplicate records in SQL Server. But Please let me know which method is the best in SQL Server 2005 and 2008 Table with Primary key and also without primary key. Thanks.
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Question by:PKTG
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by:mysteriousguy
mysteriousguy earned 75 total points
ID: 24846474
If the records are really duplicate and have no primary key, i would prefer the possibility described in this blogpost: http://blog.sqlauthority.com/2009/06/23/sql-server-2005-2008-delete-duplicate-rows/
If there is a primary key, I would determine the keys of the duplicate rows an delete them by using this key as identifier.
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Raja Jegan R earned 100 total points
ID: 24846480
This would be the best method for deleting duplicate records in SQL Server 2005 and 2008:

Hope this helps
-- Table with Primary Key
 
WITH cte(pk, rnum) as
(SELECT pk FROM 
(SELECT pk, row_number() OVER ( partition BY col1, col2 ORDER BY date_col ) rnum
 FROM urtable) temp
WHERE rnum > 1)
DELETE FROM urtable
WHERE pk IN (SELECT pk FROM cte);
 
-- Table without Primary Key but col1 and col2 defines unique records
 
WITH cte(col1, col2, rnum) AS
( SELECT col2 FROM 
(SELECT col1, col2, row_number() OVER ( partition BY col1, col2 ORDER BY date_col ) rnum
 FROM urtable) temp
WHERE rnum > 1)
DELETE FROM urtable
WHERE col1 IN ( SELECT col1 FROM cte)
AND col2 IN ( SELECT col2 FROM cte);

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by:RiteshShah
RiteshShah earned 75 total points
ID: 24846539
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