PostgreSQL trigger update with multiple if conditions

Question

I added this. However, I've no idea why it's not working. I updated member_no on customers table, not updating it on customer_tracking table. I've tried it by updating premember_no , email as well. But it's the same.

drop function if exists update_customer_tracking_on_customer_update() cascade;
drop trigger if exists update_customer_tracking_on_customer_update on customers cascade;

create function update_customer_tracking_on_customer_update() returns trigger
    language plpgsql
as
$$
begin
    if new.email != old.email then
        update customer_tracking set email = new.email where customer_tracking.customer_id = new.customer_id;
    end if;
    if new.member_no != old.member_no then
        update customer_tracking set member_no = new.member_no where customer_tracking.customer_id = new.customer_id;
    end if;
    if new.premember_no != old.premember_no then
        update customer_tracking
        set premember_no = new.premember_no
        where customer_tracking.customer_id = new.customer_id;
    end if;
    return new;
end;
$$;

-- auto-generated definition
create trigger update_cust_tracking_on_cust_update_trigger
    after update
    on customers
    for each row
execute procedure update_customer_tracking_on_customer_update();

However, if I have a separate function for each column, it all works fine. However, I don't want to have so many triggers. Is it possible to have everything in one function?

Answer 1

The purpose here seems how to keep the customer_tracking table in sync with the customer table. Often times, and always from a maintenance perspective, the best approach is no additional code at all . That is the case here: drop the customer_tracking table, drop the trigger function and create a customer_tracking view.

drop table customer_tracking; 
drop function update_customer_tracking_on_customer_update() cascade;

create or replace view customer_tracking as 
    select customer_id 
         , email
         , member_number
         , premember_no
      from customers;

See comparative example here .