declare
    object_exists exception;
    pragma exception_init (object_exists , -01430);
begin
  execute immediate
        'ALTER TABLE BOLETO ADD (ORIGENA_ID NUMBER(7),DESTINOA_ID NUMBER(7))';
    exception when object_exists then null;
end;
/
declare
    object_exists exception;
    pragma exception_init (object_exists , -01430);
begin
  execute immediate
        'ALTER TABLE CAJA ADD (ORIGENA_ID NUMBER(7),DESTINOA_ID NUMBER(7))';
    exception when object_exists then null;
end;