Delete Duplicate Records from Table in SQL

One day i got the scripts from DBA but at last i found that scripts added duplicate rows in the table and i got stuck to remove those duplicate rows from that table and finally i found a proper solution from the following link it helps and solved my problem. i am sharing this to every body it may help others as well.

found a solution from the following link :

http://stackoverflow.com/questions/18256201/sql-server-2008-delete-duplicate-rows

if you’ve any question regarding the following code i will try to answer every question

You can DELETE from a cte:

WITH cte AS (SELECT *,ROW_NUMBER() OVER(PARTITION BY uniqueid ORDER BY col2)'RowRank'
             FROM Table)
DELETE FROM cte 
WHERE RowRank > 1

The ROW_NUMBER() function assigns a number to each row. PARTITION BY is used to start the numbering over for each item in that group, in this case each value of uniqueid will start numbering at 1 and go up from there. ORDER BY determines which order the numbers go in. Since each uniqueid gets numbered starting at 1, any record with a ROW_NUMBER() greater than 1 has a duplicate uniqueid

To get an understanding of how the ROW_NUMBER() function works, just try it out:

SELECT *,ROW_NUMBER() OVER(PARTITION BY uniqueid ORDER BY col2)'RowRank'
FROM Table
ORDER BY uniqueid

You can adjust the logic of the ROW_NUMBER() function to adjust which record you’ll keep or remove.

For instance, perhaps you’d like to do this in multiple steps, first deleting records with the same last name but different first names, you could add last name to the PARTITION BY:

WITH cte AS (SELECT *,ROW_NUMBER() OVER(PARTITION BY uniqueid, col3 ORDER BY col2)'RowRank'
             FROM Table)
DELETE FROM cte 
WHERE RowRank > 1
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Delete Duplicate Records from Table in SQL

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