I have this anonymous block:
DECLARE V_DATA DATE; BEGIN V_DATA := \'01-GEN-2000\'; HR.STATISTICHE.RATINGOPERATORI (V_DATA); COMMIT; END;
here is one more option to generate date going back from now where 365 - days quanitity to move back from today, 'DD.MM.YYYY'- mask
to_char(sysdate-dbms_random.value()*365, 'DD.MM.YYYY')