SQL Server delete the duplicate rows

This short blog basically a continue version of the blog SQL Server find the duplicate rows (https://chanmingman.wordpress.com/2017/09/23/sql-server-fine-the-duplicate-rows/).

Once you find the duplicated row then you want to delete them. Before that, do store your unique row of your duplication rows first. Delete the duplicated rows then insert the unique row back into the table. You can keep this temporary unique row in another table or your RAM depend on how big is your data.

You need to append the top and bottom part to your existing SQL statement so you can delete the duplicated rows.

The top part will be

DELETE
FROM ship2

FROM Shippers1 ship2

inner
join

(

The bottom part is

)

as ship3 on

ship2.CompanyName = ship3.CompanyName

AND ship2.Phone = ship3.Phone

The complete statement as below.

DELETE
FROM ship2

FROM Shippers1 ship2

inner
join

(

SELECT ship.CompanyName, ship.Phone

From [dbo].[Shippers1] ship

inner
join

(

SELECT CompanyName, Phone,

COUNT(*)

as NumberofDuplicates

FROM [dbo].[Shippers1]

Group

by CompanyName, Phone

HAVING

COUNT(*)

> 1

)

as ship1 on

ship.CompanyName = ship1.CompanyName

AND ship.Phone = ship1.Phone

)

as ship3 on

ship2.CompanyName = ship3.CompanyName

AND ship2.Phone = ship3.Phone

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About chanmingman

Since March 2011 Microsoft Live Spaces migrated to Wordpress (http://www.pcworld.com/article/206455/Microsoft_Live_Spaces_Moves_to_WordPress_An_FAQ.html) till now, I have is over 1 million viewers. This blog is about more than 50% telling you how to resolve error messages, especial for Microsoft products. The blog also has a lot of guidance teaching you how to get stated certain Microsoft technologies. The blog also uses as a help to keep my memory. The blog is never meant to give people consulting services or silver bullet solutions. It is a contribution to the community. Thanks for your support over the years. Ming Man is Microsoft MVP since year 2006. He is a software development manager for a multinational company. With 25 years of experience in the IT field, he has developed system using Clipper, COBOL, VB5, VB6, VB.NET, Java and C #. He has been using Visual Studio (.NET) since the Beta back in year 2000. He and the team have developed many projects using .NET platform such as SCM, and HR based applications. He is familiar with the N-Tier design of business application and is also an expert with database experience in MS SQL, Oracle and AS 400.
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