On Sun, Mar 27, 2005 at 09:50:47PM -0800, Josh Berkus wrote:
> Guys,
>
> > > Well, yes, actually. Where in the documentation is a type
> > > conversion expression defined? Do we use NEW and OLD? Or the
> > > name of the column? Or something else?
> >
> > I think the ALTER TABLE page is in dire need of a "See also"
> > section, at least. And a reference to where <expression> is
> > defined would be nice to have.
>
> What I'm pointing out here is that the USING clause can't be just
> ANY expression, it needs to be a specific type of expression. And
> the docs don't explain what kind of expression is usable here.
> Even a single example would go a long way ...
I sent a patch in awhile ago that added this:
"To change an integer column containing UNIX timestamps to timestamp
with time zone via a USING clause:
ALTER TABLE foo
ALTER COLUMN foo_timestamp TYPE timestamp with time zone
USING
timestamp with time zone 'epoch' + foo_timestamp * interval '1 second';
"
That is at least something, although I agree that more examples of the
exact kind of expression would be a very good thing.
Cheers,
D
--
David Fetter david@fetter.org http://fetter.org/
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