Re: Lookup multiple tables

[Peter Brawley]

Yes, you didn't mention in your problem description that you meant to do this in a Trigger---we can't invoke Insert or Update on the Table for which an Insert or Update Trigger is defined.

Nor can we SET a new.value in an After Insert Trigger; it has to be Before Insert (best to read the manual page for a functionality before trying to use it).

Nor do your column names & field names match the problem description.

Assuming the column names you started with, in such a Trigger you can write ...

set NEW.name = (
  select p.name
  from person p  
  join owner  o on p.id_person=o.id_person
  join card   o on c.id_card=o.id_card
  where c.cardnumber = NEW.cardnumber
);