October 05, 2010

Duplicate a Column in SQL Server




Here’s a very simple but useful post that shows how to duplicate an existing column in SQL Server.

Assuming we have the following table structure with data:

CREATE TABLE #TmpTable(ColA varchar(10))
INSERT INTO #TmpTable SELECT 'ValueOne'
INSERT INTO #TmpTable SELECT 'ValueTwo'
INSERT INTO #TmpTable SELECT 'ValueThree'
INSERT INTO #TmpTable SELECT 'ValueFour'
INSERT INTO #TmpTable SELECT 'ValueFive'
INSERT INTO #TmpTable SELECT 'ValueSix'

Now to duplicate ColA, use the following code:

ALTER TABLE #TmpTable
ADD ColB varchar(10)
GO

UPDATE #TmpTable
SET ColB = ColA
GO

SELECT * FROM #TmpTable

As you can see, we have added a new column to the Table and used a simple Update statement to duplicate ColA. If the column already exists, you can avoid the ALTER TABLE.

OUTPUT

image


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About The Author

Suprotim Agarwal, ASP.NET Architecture MVP works as an Architect Consultant and provides consultancy on how to design and develop Web applications.

Suprotim is also the founder and primary contributor to DevCurry, DotNetCurry and SQLServerCurry. He has also written an EBook 51 Recipes using jQuery with ASP.NET Controls.

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