Friday, November 25, 2011

How to delete Duplicate Rows from Table

Title:How to delete duplicate rows in table using SQL Server

Description:
While working with we applications ,we have to maintain the data base is unique.Now i will describe one example on data redundancy.We just take one registration site ,which is used to register the personal details .When the user give the details multiple times ,we have to check whether the data is exist or not.If the records are exit we can delete using below query.
Note:The Duplication rows in Database tables will exists by running the data repeatedly With out  having the primary key on table.Here i have shown an example to remove the duplicate records in table

Example:
DELETE FROM Employee e1 WHERE ROW_NUMBER()<>(SELECT MIN( ROW_NUMBER())FROM EMployee e2 WHERE e1.empname= e2.empname) 
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