Re: Updates with NULL

From: Dennis Gearon <gearond(at)fireserve(dot)net>
To: Manfred Koizar <mkoi-pg(at)aon(dot)at>
Cc: shridhar_daithankar(at)persistent(dot)co(dot)in, pgsql-general(at)postgresql(dot)org
Subject: Re: Updates with NULL
Date: 2003-09-15 15:39:53
Message-ID: 3F65DD49.5030504@fireserve.net
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It's just an assignment statement, how ELSE would you assign a value,
even a NULL, to a field?

Manfred Koizar wrote:

>On Mon, 15 Sep 2003 19:34:48 +0530, "Shridhar Daithankar"
><shridhar_daithankar(at)persistent(dot)co(dot)in> wrote:
>
>
>>Update foo set somefield=NULL where somefield >9;
>>
>>Now I am not sure having something equalled with NULL is a good thig logically.
>>
>>
>
>It doesn't matter whether I agree. The standard does not. SQL92 says
>
> <set clause> ::=
> <object column> <equals operator> <update source>
>
> <equals operator> ::= =
>
> <update source> ::=
> <value expression>
> | <null specification>
> | DEFAULT
>
> <null specification> ::=
> NULL
>
>SQL99 is much more verbose and difficult to read, but it is very clear
>that the assignment operator in a set clause has to be "=".
>
>Servus
> Manfred
>
>---------------------------(end of broadcast)---------------------------
>TIP 4: Don't 'kill -9' the postmaster
>
>
>

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