On 01/01/2013 10:17 AM, Rafał Pietrak wrote:
Hello the list,
As far as I can tell from a quick search through postgresql
documentation, the OLD.* pseudorelation is not available for INSERT
triggers and rules. And a little googleing I did, haven't pointed me to
anything relevant to the following. My apology if I miss in my search
such discussion happening earlier (I apreciate a pointer, where I can
see pros and cons that've been raisen back then);
If not, I think having OLD.* in INSERT rules/triggers is worth pondering.
The thing is, that it would be a valuable tool to mimic table-propper
functionality by a view. The OLD.* preudorelation on INSERT could
provide column defaults from the underlaying table definition.
like:
CREATE TABLE test (tm timestamp default now(), info text);
CREATE TABLE test_view AS SELECT * FROM test;
CREATE RULE with_defaults AS ON INSERT to test_view DO INSTEAD INSERT
INTO test (tm,info) VALUES ( //COALESCE(NEW.tm, OLD.tm), NEW.text);
so:
INSERT INTO test_view (info) VALUES ('hello');
and:
INSERT INTO test_view (tm, info) VALUES (null, 'hello');
both work just as if test_view was a TABLE with a default tm value defined.
http://www.postgresql.org/docs/9.2/interactive/sql-alterview.html
"SET/DROP DEFAULT
These forms set or remove the default value for a column. A default
value associated with a view column is inserted into INSERT statements
on the view before the view's ON INSERT rule is applied, if the INSERT
does not specify a value for the column."
It is not quite the same, but close.
-R
--
Adrian Klaver
adrian.klaver@xxxxxxxxx
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