Re: Triggering a table id from a sequence

am 10.04.2006, um 16:53:27 -0700 mailte Lan Barnes folgendes:
> My desire is to have a table auto update an "id" sequence on every
> insert, relieving the front end program of the responsibility.
>
> I've never written a trigger. I imagine that there may be a contrib
> trove of them.
>
> There may also be an easier way to approach the problem. Please feel
> free to refer me to books or web sites.

A simple way for this is a RULE. (on insert to <table> do also)

test=# create table foo (id int);
CREATE TABLE
test=# create sequence foo_seq;
CREATE SEQUENCE
test=# create rule foo_rule as on insert to foo do also select nextval('foo_seq');
CREATE RULE
test=# select * from foo_seq ;
sequence_name | last_value | increment_by | max_value | min_value | cache_value | log_cnt | is_cycled | is_called
---------------+------------+--------------+---------------------+-----------+-------------+---------+-----------+-----------
foo_seq | 1 | 1 | 9223372036854775807 | 1 | 1 | 1 | f | f
(1 row)

test=# insert into foo values (5);
nextval
---------
1
(1 row)

test=# insert into foo values (4);
nextval
---------
2
(1 row)

test=# insert into foo values (3);
nextval
---------
3
(1 row)

test=# select last_value from foo_seq ;
last_value
------------
3
(1 row)

http://www.postgresql.org/docs/8.1/interactive/rules-update.html

HTH, Andreas
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Andreas Kretschmer (Kontakt: siehe Header)
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