create or replace trigger <triggername>
 before/after insert or update or delete
 on <tablename> 
 REFERENCING NEW AS <newROW> OLD AS <oldROW>
 for each row/for each statement
 when (<condition>)
 DECLARE
    -- Déclaration des variables
 BEGIN
    if INSERTING then
     ...
    end if;
    if UPDATING then
     ...
    end if;
    if DELETING then
     ...
    end if;
 EXCEPTION
    -- Traitement en cas d'exception
 END <triggername>;