Обсуждение: regexp on null

On Fri, Sep 10, 2010 at 9:00 AM, Gauthier, Dave <dave.gauthier@intel.com> wrote:

> Is there a way to regexp match on a null value?

I would say no.

>  Or is it necessary to OR in a .... "or x is null"?

you could use a

COALESCE( text_column, '') ~ E'MyRegEx';

Or perhaps:
 ( text_column ~ E'MyRegEx' ) IS UNKNOWN
 might work.


--
Regards,
Richard Broersma Jr.

Visit the Los Angeles PostgreSQL Users Group (LAPUG)
http://pugs.postgresql.org/lapug

Ya, I kinda knew about these approaches.  The problem ahs to do with novice users who don't know about coalesce or
or;inga check ofr nulls.  I was hoping there was some special regexp expression that would match to a null. 

Thanks for the quick response, and have a great weekend !

-----Original Message-----
From: Richard Broersma [mailto:richard.broersma@gmail.com]
Sent: Friday, September 10, 2010 12:19 PM
To: Gauthier, Dave
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] regexp on null

On Fri, Sep 10, 2010 at 9:00 AM, Gauthier, Dave <dave.gauthier@intel.com> wrote:

> Is there a way to regexp match on a null value?

I would say no.

>  Or is it necessary to OR in a .... "or x is null"?

you could use a

COALESCE( text_column, '') ~ E'MyRegEx';

Or perhaps:
 ( text_column ~ E'MyRegEx' ) IS UNKNOWN
 might work.


--
Regards,
Richard Broersma Jr.

Visit the Los Angeles PostgreSQL Users Group (LAPUG)
http://pugs.postgresql.org/lapug

On Fri, Sep 10, 2010 at 9:56 AM, Gauthier, Dave <dave.gauthier@intel.com> wrote:
> Ya, I kinda knew about these approaches.  The problem ahs to do with novice users who don't know about coalesce or
or;inga check ofr nulls.  I was hoping there was some special regexp expression that would match to a null. 


Perhaps the easiest was to help such users is to make the column(s) in
question NOT NULL DEFAULT ''.

--
Regards,
Richard Broersma Jr.

Visit the Los Angeles PostgreSQL Users Group (LAPUG)
http://pugs.postgresql.org/lapug

On Fri, Sep 10, 2010 at 10:25:55AM -0700, Richard Broersma wrote:
> On Fri, Sep 10, 2010 at 9:56 AM, Gauthier, Dave <dave.gauthier@intel.com> wrote:
> > Ya, I kinda knew about these approaches.  The problem ahs to do
> > with novice users who don't know about coalesce or or;ing a check
> > ofr nulls.  I was hoping there was some special regexp expression
> > that would match to a null.
>
> Perhaps the easiest was to help such users is to make the column(s)
> in question NOT NULL DEFAULT ''.

I think it's a very, very bad idea to make a default like that.  I'm
aware that it's common in one of those Oracle properties, but it needs
to stay confined there.

Cheers,
David.
--
David Fetter <david@fetter.org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
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