Thanks for the reply. I confirm the behaviour. Your explanation makes
sense if I consider having read that with an update the is a complete
new record version written.
Am 10.11.2023 um 14:35 schrieb David G. Johnston:
On Friday, November 10, 2023, Thiemo Kellner
<thi...@gelassene-pferde.biz> wrote:
Hi all
I have a view, that is a join over 4 tables (the setup of the rule
question). I want to update the central table over the view (by an
instead-of trigger). How can I determine, whether an attribute
should get set to NULL, "new.XYZ is null" or whether it should be
left alone. Is there a leave-me-alone function determining,
whether an attribute is in the set clause of an update statement.
I am thinking along the line code in the trigger function like
update TABLE
set XYZ = case
when leave-me-alone (new.XYZ) then old.XYZ
else new.XYZ
end;
And what about the where condition... hm, guess I am a bit confused.
IIUC, The NEW record is complete, with every value as it should be in
the newly saved tuple. There is no leave-me-alone concept. You don’t
get to know if the column was specified or not in the update command.
David J.
