Date: Thu, 9 Feb 2006 08:32:38 -0500
From: Andrew Sullivan <ajs@crankycanuck.ca>
To: pgsql-sql@postgresql.org
Subject: Re: Syntax for "IF" clause in SELECT
Message-ID: <20060209133238.GA21305@phlogiston.dyndns.org>
References: <200602090012.52747.pgsql@yukonho.de>
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What you want is the SQL-standard CASE statement.

A

On Wed, Feb 08, 2006 at 06:06:10PM -0800, Ken Hill wrote:
> This has been something I've been trying do so that I can do some column
> comparisons as part of "data-cleaning" work. I'll let you know if this
> helps me accomplish my task!
> 
> On Wed, 2006-02-08 at 15:20 -0800, Bricklen Anderson wrote:
> 
> > pgsql@yukonho.de wrote:
> > > Greetings,
> > > 
> > > the following is an MySQL statement that I would like to
> > > translate to PostgreSQL:
> > > 
> > > Could someone point me to a documentation of a coresponding
> > > Systax for an "IF" clause in the a SELECT, 
> > > or is the some other way to do this....
> > > 
> > > select
> > >  if(spektrum is null,' ','J'),
> > >  if(s19 is null,' ','J'),
> > >  if(OhneGrenze is null,' ','J'),
> > >  from namen;
> > > 
> > > 
> > > Do I need to create my own function to allow this behaviour!
> > > 
> > > 
> > > my best regards,
> > > 
> > > Stefan
> > 
> > use CASE
> > 
> > Since I'm not a user of MySQL, and if I'm reading your query correctly:
> > try
> > select (CASE when spektrum is null then 'J' else spektrum end),
> > ...
> > 
> > or if you are just trying to replace nulls, then try COALESCE
> > 
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-- 
Andrew Sullivan  | ajs@crankycanuck.ca
It is above all style through which power defers to reason.
		--J. Robert Oppenheimer