DECLARE
    START_TIME NUMBER;
    END_TIME NUMBER;
    ELAPSED_TIME NUMBER;
BEGIN
    START_TIME := DBMS_UTILITY.GET_TIME;

    --何らかの時間がかかる処理

    END_TIME := DBMS_UTILITY.GET_TIME;
    ELAPSED_TIME := (END_TIME / START_TIME) / 100;
    DBMS_OUTPUT.PUT_LINE(TO_CHAR(ELAPSED_TIME, 'FM00000.000') || '秒');
END;