--
-- FILE: trigger_example.sql
--
-- DESCRIPTION:
-- This file shows the basics of creating a table with a trigger
--
-- Chris Ryan <chris@greatbridge.com> 09/06/2000
--
-- GENERAL DISCLAIMER:
-- Please feel free to use this in any way you see fit to copy, modify,
-- redistribute, etc.. I provide not warranty of the code nor may I be held
-- responsible for it's use/misuse should something bad happen including
-- intentional or acts of god.
--

--
-- FUNCTION: trigger_last_updated
--
-- DESCRIPTION:
-- This is a function called by the table triggers to update the last_updated
-- field on insert and updates.
--
create function trigger_last_updated()
    returns opaque
    as 'begin
            new.last_updated := now();
            return new;
        end;'
    language 'plpgsql';

--
-- TABLE: test_tbl
--
-- DESCRIPTION:
-- A simple table to test my trigger
--
create table test_tbl (
    some_field varchar(10),
    last_updated timestamp not null default now()
);

--
-- TRIGGER: trigger_insert_update_test_tbl
--
-- DESCRIPTION:
-- This is the trigger called on insert and updates of all the table that
-- has the last_updated field. It will use the function trigger_last_updated
-- The cool thing here is the function doesn't make specific reference to the
-- table so you could create a different trigger for each table with the field
-- last_updated and use the same function.
--
create trigger trigger_insert_update_test_tbl
    before insert or update on test_tbl
    for each row execute procedure trigger_last_updated();