Re: Deleting columns in a table

Thanks guys, actually I am using Oracle 7 so I guess I am going to have to drop tables and recreate. Thanks, Dietrich

dgdss wrote:

> Sorry of course you are right in 8i you can drop a column, I use v8 here.
> Thanks for the correction.
>
> "wysza" <awysza_at_yahoo.com> wrote in message
> news:Ert56.2129$bR3.405519_at_typhoon2.ba-dsg.net...
> > You can drop column in 8i .
> >
> > 1.
> > alter table table_name DROP COLUMN col_name CASCADE CONSTRAINTS CHECKPOIN
> > 1000;
> >
> > Checkpoints are usefull when you have large tables and small rollbacks.
> > 1000 - it means every 1000 records make a checkpoint.
> > When this operation starts, table status is set to INVALID until this
> > operation is finished.
> > If sth happens to DB in the mean time and the instance hase to go down,
 this
> > table will be INVALID after bringing instance up. In this case, to resume
> > this operation you have to do:
> >
> > alter table table_name DROP COLUMNS CONTINUE;
> >
> > This statement, however, will give you an error if the status of
 table_name
> > is VALID.
> >
> > 2.
> > You can also set column as UNUSED.
> >
> > alter table table_name SET UNUSED COLUMN col_name;
> >
> > and
> > alter table table_name DROP UNUSED COLUMNS CHECKPOINT 1000;
> >
> > and (in case of accident )
> > alter table table_name DROP COLUMNS CONTINUE CHECKPOINT 1000;
> >
> > Here, the performance is much better. When you set the column as UNUSED,
 you
> > Oracle will behave as if this column didn't exist (desc will not show it).
> > Setting cols as UNUSED is much better when you want to delete more than
 one
> > column from a table.
> >
> > hope this help
> >
> >
> > "dgdss" <dgdss_at_hotmail.com> wrote in message
> > news:dDs56.224493$_5.50585207_at_news4.rdc1.on.home.com...
> > > You are going to have to export the table and create a new table without
 th
> > > esaid column, then import into the new table. You can't just drop a
 column.
> > > "Dietrich Johnson" <djohnson_at_polaris.umuc.edu> wrote in message
> > > news:3A563BB3.6DFCEA0B_at_polaris.umuc.edu...
> > > > Is there an easy way to delete a column that has no constraints.
> > > >
> > >
> > >
> >
> >
Received on Sat Jan 06 2001 - 01:55:25 CET