Re: BUG #6064: != NULL, <> NULL do not work [sec=UNCLASSIFIED]

Thanks Craig,

The real problem here then is that the documentation showing
the boolean comparison operators does not mention this quirk, which I=20
accept may be a standard quirk but it's still a quirk. You just
wouldn't go looking for that flag unless you had any inkling that
it might exist.

And indeed the parser does not generate warnings either.

Regards,
Michael




-----Original Message-----
From: Craig Ringer [mailto:craig@postnewspapers.com.au]
Sent: Sun 6/19/2011 6:30 PM
To: Kevin Grittner
Cc: Pilling, Michael; pgsql-bugs@postgresql.org
Subject: Re: [BUGS] BUG #6064: !=3D NULL, <> NULL do not work
=20
On 06/17/2011 10:20 PM, Kevin Grittner wrote:
> "Michael Pilling"<Michael.Pilling@dsto.defence.gov.au>  wrote:
>
>> A reasonable programmer would expect !=3D NULL,<>  NULL and IS NOT
>> NULL to be synonyms.
>
> Only if that programmer was not aware of the SQL standard and had
> not worked much with a standard-conforming database.

Yep, and if they want to continue working that way, they can use the=20
flag intended for compatibility with Microsoft Access that makes NULL =3D=
=20
NULL result in 't' instead of NULL.

http://www.postgresql.org/docs/current/static/runtime-config-compatible.htm=
l#GUC-TRANSFORM-NULL-EQUALS

Note that this flag is very specifically limited to equality=20
comparisions using the '=3D' operator. It won't make NULL behave as a=20
value in any other way. For example, 1 > NULL will still return NULL.

--
Craig Ringer


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