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Thread: Problems with Triggers

Problems with Triggers

From
Sebastian Böck
Date:
Hello,

is there a simple operator to determine whether the OLD.value and
NEW.value are different. The <> operator is not working on NULL's.

I need something like this:
NEW.val <> Old.val OR
NEW.val IS NULL AND OLD.val IS NOT NULL OR
NEW.val IS NOT NULL AND OLD.val IS NULL

Thanks in advance

Sebastian

Re: Problems with Triggers

From
Martin Marques
Date:
El Jue 15 Abr 2004 08:55, Sebastian Böck escribió:
> Hello,
>
> is there a simple operator to determine whether the OLD.value and
> NEW.value are different. The <> operator is not working on NULL's.
>
> I need something like this:
> NEW.val <> Old.val OR
> NEW.val IS NULL AND OLD.val IS NOT NULL OR
> NEW.val IS NOT NULL AND OLD.val IS NULL

(NEW.val <> Old.val) OR
(NEW.val IS NULL AND OLD.val IS NOT NULL) OR
(NEW.val IS NOT NULL AND OLD.val IS NULL)

You forgot the parenthesis, to group the conditions accordingly

--
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-----------------------------------------------------------------
Martín Marqués        | select 'mmarques' || '@' || 'unl.edu.ar'
Centro de Telematica  |  DBA, Programador, Administrador
             Universidad Nacional
                  del Litoral
-----------------------------------------------------------------

Re: Problems with Triggers

From
Sebastian Böck
Date:
Martin Marques wrote:
> El Jue 15 Abr 2004 08:55, Sebastian Böck escribió:
>
>>Hello,
>>
>>is there a simple operator to determine whether the OLD.value and
>>NEW.value are different. The <> operator is not working on NULL's.
>>
>>I need something like this:
>>NEW.val <> Old.val OR
>>NEW.val IS NULL AND OLD.val IS NOT NULL OR
>>NEW.val IS NOT NULL AND OLD.val IS NULL
>
>
> (NEW.val <> Old.val) OR
> (NEW.val IS NULL AND OLD.val IS NOT NULL) OR
> (NEW.val IS NOT NULL AND OLD.val IS NULL)
>
> You forgot the parenthesis, to group the conditions accordingly

Yes i did in my mail, but that's not the question.
I wanted to know if there is a special operator that does exactly
this.

Sebastian

Re: Problems with Triggers

From
Stephan Szabo
Date:
On Thu, 15 Apr 2004, [ISO-8859-1] Sebastian B�ck wrote:

> is there a simple operator to determine whether the OLD.value and
> NEW.value are different. The <> operator is not working on NULL's.

Not as far as I know, although I think you can simplify the last part as
(NEW.val IS NULL <> OLD.val IS NULL)

> I need something like this:
> NEW.val <> Old.val OR
> NEW.val IS NULL AND OLD.val IS NOT NULL OR
> NEW.val IS NOT NULL AND OLD.val IS NULL