How to convert a fixed column to a computed column?

Question

How to convert a fixed column to a computed column?

Sumit Rastogi

SSC Eights!

Points: 838
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June 7, 2011 at 9:10 am

#237521

Hi,
I have an already existing table say TABLE1 with some records, it have a column say COL1 VARCHAR(1) NOT NULL having values Y or N. I want to convert this Fixed Column to Computed Column on certain criteria say (CASE WHEN ISNULL([END_DATE], GETDATE()) >= GETDATE() THEN 'Y' ELSE 'N' END).
Please help!!!!
Sumit Rastogi

Viewing 5 posts - 1 through 4 (of 4 total)

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HowardW One Orange Chip Points: 29109 More actions · Answer 1

You'd need to drop the existing column then create the computed one.

Computed columns can't be created/modified through an alter column statement (the same goes for if you change the definition of a existing computed column)

Naginder Pathania Right there with Babe Points: 722 More actions · Answer 2

Hi

you can not convert existing column with computed expression.You can add new column as Computed one in a existing table.

Thanks,

Naginder

Sumit Rastogi SSC Eights! Points: 838 More actions · Answer 3

Thanks for the reply....

That I know thats why I already describe in the question that the table already have some records (say about .2 millions) so I think dropping is not a good idea.

Sumit

HowardW One Orange Chip Points: 29109 More actions · Answer 4

You could rename the old column to something else using sp_rename, then create the computed column. Either way you're going to want to drop the existing column at some point