Remove duplicate records from a table in SQL Server

Shailendra Chauhan  Print 
Posted On : 24 Aug 2012
Updated On : 24 Sep 2016
Total Views : 247,390

Sometimes we required to remove duplicate records from a table although table has a UniqueID Column with identity. In this article, I would like to share a best way to delete duplicate records from a table in SQL Server.

Suppose we have below Employee table in SQL Server.

 CREATE TABLE dbo.Employee
( 
EmpID int IDENTITY(1,1) NOT NULL, 
Name varchar(55) NULL, 
Salary decimal(10, 2) NULL, 
Designation varchar(20) NULL
 ) 

The data in this table is as shown below:

Remove Duplicate Records by using ROW_NUMBER()

 WITH TempEmp (Name,duplicateRecCount)
AS
(
SELECT Name,ROW_NUMBER() OVER(PARTITION by Name, Salary ORDER BY Name) 
AS duplicateRecCount
FROM dbo.Employee
)
--Now Delete Duplicate Records
DELETE FROM TempEmp
WHERE duplicateRecCount > 1 
 --See affected table
Select * from Employee 

For more help about ROW_NUMBER(), please follow the MSDN link.

Summary

In this article, I expose how can you remove duplicate records from a table in SQL Server. I hope after reading this article you will be able to use these tips. I would like to have feedback from my blog readers. Please post your feedback, question, or comments about this article.



ABOUT AUTHOR

Shailendra Chauhan
An Entrepreneur, Microsoft MVP, Author, Architect And Corporate Trainer

He is a founder and CEO of Dot Net Tricks. He is the author of some of most popular e-books which encompass technical Interview on Node.js Interview Questions and Answers, ASP.NET MVC Interview Questions and Answers, AngularJS Interview Questions and Answers and LINQ Interview Questions and AnswersKnow more...

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