Re: simple update on boolean

You could use a COALESCE instead of a case statement for simple case
like this. The below will treat a NULL as false and then when you do
not it becomes true. So NULLS will be set to true

UPDATE boolean_column SET boolean_column = NOT COALESCE(boolean_column,
false)

hope that helps,
Regina

-----Original Message-----
From: pgsql-general-owner(at)postgresql(dot)org
[mailto:pgsql-general-owner(at)postgresql(dot)org] On Behalf Of Ivan Sergio
Borgonovo
Sent: Thursday, December 06, 2007 10:19 AM
To: pgsql-general(at)postgresql(dot)org
Subject: Re: [GENERAL] simple update on boolean

On Thu, 06 Dec 2007 14:53:13 +0100
Cedric Boudin <cedric(at)dreamgnu(dot)com> wrote:

> > What if boolean_column is NULL?
> >
> > btw set bolean_column= not bolean_column works "as expected".
> >
> > template1=# select (not 't'::boolean),(not 'f'::boolean),(not
> > NULL::boolean);
> >
> > ?column? | ?column? | ?column?
> > ----------+----------+----------
> > f | t |
> > (1 riga)

> If it was null before it has to be null afterwards (IMHO).
> If you don't want to have null,
> take care of it somewhere else but not here.

That is the "as expected" part.

The "case" case, other than being more verbose, do more than what I
would expect since all NULL are converted to t.

template1=# select case when NULL then 'f'::boolean else 't'::boolean
end;

case
------
t
(1 riga)

--
Ivan Sergio Borgonovo
http://www.webthatworks.it

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