declare
  object_exists  exception;
  except_02275  exception;

  pragma exception_init (object_exists  , -01430);
  pragma exception_init (except_02275  , -02275);
begin
	execute immediate 'ALTER TABLE PACOTE_TARIFA ADD CONSTRAINT FK_CATEGORIA FOREIGN KEY (CATEGORIA_ID) REFERENCES CATEGORIA (CATEGORIA_ID)';

  exception 
    when object_exists  then null;
    when except_02275  then null;
end;