Re: Is there a way to test for UNASSIGNED in pl/pgsql

On Mon, Oct 29, 2012 at 11:26 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
> Hello
>
>
> 2012/10/29 Hannu Krosing <hannu@2ndquadrant.com>:
>> Hi
>>
>> Is there a way to test for a variable being unassigned in pl/pgsql ?
>>
>> I'm writing an audit trigger where I'd like to save full before and
>> after images into audit log and I really do not like to do
>>
>> IF TG_OP IN ('INSERT', 'UPDATE') ...
>>
>> I'd like rather better if i could just write
>>
>> IF NEW IS ASSIGNED THEN ...
>>
>> or even use it straight
>>
>> null_if_unnasigned(NEW)
>>
>> overriding
>>
>> coalesce(NEW, NULL)
>>
>> for the same purpose would also be ok
>>
>
> I don't know about any way, how to do it. It is little bit hard,
> because it means test of state plpgsql variable (and plpgsql property)
> from SQL expression, and it is not possible from SQL.
>
> we can design some new variant of IF statement, where parameter is
> test of validity some variable instead SQL expression
>
> some like
>
> IF DEFINED NEW THEN ...

how is that different from SQL coalesce()?

merlin