DECLARE
    start_time number;
    end_time   number;
    interval   number;
    var        number :=0;
BEGIN
    start_time := DBMS_UTILITY.get_time();
    for i in 1..1000000 loop
        var := var+1;                               -- or do anything
    end loop;
    end_time := DBMS_UTILITY.get_time();
    interval := (end_time - start_time) * 10;       -- make it in milliseconds

    DBMS_OUTPUT.put_line('This process took ' || interval || ' milliseconds');
END;