SQL Server find the duplicate rows

This short blog shows you how to list the data in duplicated rows in SQL Server.

Let’s look at the Northwind (https://chanmingman.wordpress.com/2012/03/18/northwind-in-microsoft-sql-server-2012/) database in SQL Server. You can see the Shippers table has 2 duplicate rows, United Package.


As first, we find out which rows are duplicated, and how many duplication are there.

SELECT CompanyName,
COUNT(*)
as NumberofDuplicates

FROM [dbo].[Shippers]

Group
by CompanyName

HAVING
COUNT(*)
> 1

Order
by CompanyName


Then we list the content of those rows.

SELECT ship.CompanyName, ship.Phone

From [dbo].[Shippers] ship

inner
join

(

SELECT CompanyName, Phone,
COUNT(*)
as NumberofDuplicates

FROM [dbo].[Shippers]

Group
by CompanyName, Phone

HAVING
COUNT(*)
> 1

)
as ship1 on

ship.CompanyName = ship1.CompanyName

AND ship.Phone = ship1.Phone

Order
by ship.CompanyName


Reference:

https://stackoverflow.com/questions/2594829/finding-duplicate-values-in-a-sql-table

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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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One Response to SQL Server find the duplicate rows

  1. Pingback: SQL Server delete the duplicate rows | Chanmingman's Blog

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