Re: ALTERING A TABLE

Steve Wampler wrote:
>
> Ron Peterson wrote:
> >
> >
> > You can't use ALTER TABLE to change a field's data description. You'll
> > have to make a new table. Then use SELECT INTO to move your data. Then
> > DROP TABLE oldtable. Then ALTER TABLE tablename RENAME TO newname.
>
> Would this really work? According to the docs, SELECT INTO creates a
> new table (which must not yet exist). So this new table
> would have the same field data descriptions as the original, right?
>
> Is the documentation wrong?

No, the doc is at least right that a new table is created. Not sure what
it does if the table already exists.

I do this task by the following sequence (psuedo-sql here):

select into temp_mytable * from mytable;
drop mytable;
create table mytable (...new defn...);
insert into mytable (...)
select ... from temp_mytable

And that works pretty well. Don't forget you'll have to drop/reload all
dependent functions/triggers. And if you're using a SERIAL column, don't
mistakenly nuke your sequence object (mytable_id_seq) if you're using one
as a primary key generator, otherwise you'll reset the sequence and get
massive confusion.

Regards,
Ed Loehr