Kent,
I suggest you read:
http://www.postgresql.org/docs/7.3/interactive/plpgsql-trigger.html
I found it very useful myself, and it should answer (almost?) all your
questions.
Note that you will need to add either pl/pgsql or pl/TCL to your
database to do triggers.
The docs. for both languages are at:
http://www.postgresql.org/docs/7.3/interactive/programmer-pl.html
Andrew
Kent L. Nasveschuk wrote:
>Hello,
>I'm trying to write a trigger that upon inserting a value in a table
>another table is decremented. Something that could be used in an
>inventory system, for example. I know it can be done easily outside
>POSTGRES with PHP but in this case I would like the database to handle
>it.
>
>
>Example:
>
>create table order (
> order_number integer not null default
>nextval('order_number_seq'::text),
> itemid number integer references inventory,
> item_amt integer,
> cost numeric(3,2),
> constraint order_pk primary key(order_number)
>);
>
>create table inventory (
> itemid integer not null default nexval('itemid_seq'::text),
> onhand integer not null default 0,
> onorder integer not null default 0,
> desc varchar(30) not null,
> cost numeric(3,2) not null,
> constraint inventory_pk primary key(itemid)
>);
>
>Can you give me some direction on how to do this. In this case decrement
>the inventory by the amount of the order for that particular item. I'm
>not sure how to pass variables to triggers and/or functions.
>
>Thank you
>
>
>
>
