On 10/29/2012 05:36 PM, Merlin Moncure wrote:
On Mon, Oct 29, 2012 at 11:26 AM, Pavel Stehule <pavel.steh...@gmail.com> wrote:
Hello
2012/10/29 Hannu Krosing <ha...@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()?
It seems that the "variable is unassigned" comes before SQL has a chance
to see it.
Would just converting UNDEFINED to NULL be a very bad idea ?
It happens so in many places in SQL queries?
And then in some this NULL is coverted to FALSE :)
--------------------------
Hannu
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