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How to convert a fixed column to a computed column?

  • 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

  • June 7, 2011 at 9:17 am

    #1335085

    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)

  • June 7, 2011 at 10:08 am

    #1335139

    Hi

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

    Thanks,

    Naginder

  • June 7, 2011 at 11:10 pm

    #1335443

    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

  • June 8, 2011 at 1:51 am

    #1335474

    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

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