create?table?emp1?select?*?from?emp?where?1=2;

create?or?replace?trigger?tri_operation_dml
?after?insert?or?delete?or?update?on?emp
?for?each?row
?begin??
?insert?into?emp1(ename)??select?case?when?:old.ename?is?null?then?:new.ename?else?:old.ename?end??from?dual;
?end;