Skip site navigation (1) Skip section navigation (2)

Re: Missing doc on expression format for ALTER TABLE

From: David Fetter <david(at)fetter(dot)org>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>,Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-docs(at)postgresql(dot)org
Subject: Re: Missing doc on expression format for ALTER TABLE
Date: 2005-03-28 16:22:44
Message-ID: 20050328162244.GB11442@fetter.org (view raw or flat)
Thread:
Lists: pgsql-docs
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(at)fetter(dot)org http://fetter.org/
phone: +1 510 893 6100   mobile: +1 415 235 3778

Remember to vote!

In response to

pgsql-docs by date

Next:From: Jim C. NasbyDate: 2005-03-28 20:54:23
Subject: Re: Version information in docs
Previous:From: Thomas F.O'ConnellDate: 2005-03-28 16:03:49
Subject: Re: Version information in docs

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group