Need Help With Query Using Aggregation

Question

If I have a table, defined like this:
CREATE TABLE range_test
range_id NUMBER(20) NOT NULL,
grade CHAR(1) NOT NULL,
lower_bound_of_range NUMBER(5,2) NOT NULL,
upper_bound_of_range NUMBER(5,2) NOT NULL,
received_date_time_stamp TIMESTAMP DEFAULT SYSTIMESTAMP NOT NULL
And I wanted to query the table to find the range associated with the last inserted row for each 'grade' (e.g. 'A', 'B', 'C', etc), how would I go about that?
I want something like the following, but I know that this won't work right:
SELECT
grade,
lower_bounding_of_range,
upper_bounding_of_range,
max(received_date_time_stamp)
FROM
range_test GROUP BY received_date_time_stamp;
Thanks for your help. . .I'm frustrating myself with this one and I think it should be possible without having to use PL/SQL (i.e. SQL aggregate functions or sub-queries should work).

Answer 1

Perhaps something along the lines of...
SQL> ed
Wrote file afiedt.buf
  1  select deptno, empno, ename, hiredate
  2  from emp
  3* order by deptno, empno
SQL> /
    DEPTNO      EMPNO ENAME      HIREDATE
        10       7782 CLARK      09-JUN-1981 00:00:00
        10       7839 KING       17-NOV-1981 00:00:00
        10       7934 MILLER     23-JAN-1982 00:00:00
        20       7369 SMITH      17-DEC-1980 00:00:00
        20       7566 JONES      02-APR-1981 00:00:00
        20       7788 SCOTT      19-APR-1987 00:00:00
        20       7876 ADAMS      23-MAY-1987 00:00:00
        20       7902 FORD       03-DEC-1981 00:00:00
        30       7499 ALLEN      20-FEB-1981 00:00:00
        30       7521 WARD       22-FEB-1981 00:00:00
        30       7654 MARTIN     28-SEP-1981 00:00:00
        30       7698 BLAKE      01-MAY-1981 00:00:00
        30       7844 TURNER     08-SEP-1981 00:00:00
        30       7900 JAMES      03-DEC-1981 00:00:00
14 rows selected.
SQL> ed
Wrote file afiedt.buf
  1  select deptno, empno, ename, hiredate
  2  from (
  3        select deptno, empno, ename, hiredate
  4              ,row_number() over (partition by deptno order by hiredate desc) as rn
  5        from emp
  6       )
  7  where rn = 1
  8* order by deptno, empno
SQL> /
    DEPTNO      EMPNO ENAME      HIREDATE
        10       7934 MILLER     23-JAN-1982 00:00:00
        20       7876 ADAMS      23-MAY-1987 00:00:00
        30       7900 JAMES      03-DEC-1981 00:00:00
SQL>