Updating current timestamp of multiple tables through single trigger function - postgresql

Question

I have 2 tables created :- Table Banks and Branch. Both the tables have column last_updated(which means when was the record last updated.) I have created after update trigger for each row on both the tables. The trigger and trigger function looks like below :-
create trigger banks_upd_trg
after update of phone_no
on Banks
FOR EACH ROW
EXECUTE PROCEDURE bankdetails_upd();
create trigger branch_upd_trg
after update of email_address
on Branch
FOR EACH ROW
EXECUTE PROCEDURE bankdetails_upd();
create or replace FUNCTION bankdetails_upd()
RETURNS trigger AS
$BODY$
BEGIN
EXECUTE format('update %I.%I SET last_updated=current_timestamp where id=new.id',TG_SHEMA_NAME,TG_TABLE_NAME)
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql
The trigger is getting executed successfully but isn't working at the time of updating phone_no and email_address column in Banks and Branch table respectively.

Answer 1

No need for dynamic SQL or an UPDATE statement.
Use a before trigger and assign the value to the NEW record.
create or replace FUNCTION bankdetails_upd()
RETURNS trigger AS
$BODY$
BEGIN
new.last_updated := current_timestamp;
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql;
create trigger banks_upd_trg
BEFORE update of phone_no
on Banks
FOR EACH ROW
EXECUTE PROCEDURE bankdetails_upd();
create trigger branch_upd_trg
BEFORE update of email_address
on Branch
FOR EACH ROW
EXECUTE PROCEDURE bankdetails_upd();