I think you want to use foreign keys which can give you these checks. So add a foreign key to create a link between rad_id of both tables.
regards, Bastiaan
Madison Kelly wrote:
Hi all,
I've been using a procedure to make a copy of data in my public schema into a history schema on UPDATE and INSERTs.
To prevent duplicate entries in the history, I have to lead in the current data, compare it in my program and then decided whether something has actually changed or not before doing an update. This strikes me as wasteful coding and something I should be able to do in my procedure.
Given the following example tables and procedure, how could I go about changing it to prevent duplicate/unchanged entries being saved to the history schema? Even a pointer to a relevant section of the docs would be appreciated... My knowledge of procedures is pretty weak. :)
Madi
CREATE TABLE radical ( rad_id integer primary key default(nextval('id_seq')), rad_char text not null, rad_name text );
CREATE TABLE history.radical ( rad_id integer not null, rad_char text not null, rad_name text, hist_id integer not null default(nextval('hist_seq')), modified_date timestamp default now() );
CREATE FUNCTION history_radical() RETURNS "trigger" AS $$ DECLARE hist_radical RECORD; BEGIN SELECT INTO hist_radical * FROM public.radical WHERE rad_id=new.rad_id; INSERT INTO history.radical (rad_id, rad_char, rad_name) VALUES (hist_radical.rad_id, hist_radical.rad_char, hist_radical.rad_name); RETURN NULL; END;$$ LANGUAGE plpgsql;
CREATE TRIGGER trig_radical AFTER INSERT OR UPDATE ON "radical" FOR EACH ROW EXECUTE PROCEDURE history_radical();