declare
    column_exists exception;
    pragma exception_init (column_exists , -00001);
begin
    execute immediate 'update 
(select PF.INDLECTURA,PF.FECMODIF
from PERFIL_FUNCION PF
inner join FUNCION_SISTEMA FS on  FS.FUNCIONSISTEMA_ID = PF.FUNCIONSISTEMA_ID
where FS.SISTEMA_ID=2 and PF.INDLECTURA=1) TB
SET TB.INDLECTURA=0,
TB.FECMODIF=SYSDATE';
    exception when column_exists then null;
end;