Help with sql subquery/grouping

Question

Hi... having trouble getting this query to work. Here's the table and data:
create table mytable (
rec_num number,
status_num number,
status_date date
insert into mytable values (1,1,'01-AUG-2006');
insert into mytable values (1,2,'14-AUG-2006');
insert into mytable values (1,8,'01-SEP-2006');
insert into mytable values (1,3,'15-SEP-2006');
insert into mytable values (1,2,'03-SEP-2006');
insert into mytable values (2,2,'17-AUG-2006');
insert into mytable values (3,2,'02-SEP-2006');
insert into mytable values (3,4,'07-SEP-2006');
insert into mytable values (4,1,'18-SEP-2006');
insert into mytable values (4,4,'27-SEP-2006');
insert into mytable values (4,2,'18-SEP-2006');
insert into mytable values (5,1,'01-OCT-2006');
insert into mytable values (5,2,'03-OCT-2006');
insert into mytable values (5,3,'05-OCT-2006');
insert into mytable values (6,1,'01-OCT-2006');
insert into mytable values (7,2,'14-OCT-2006');
insert into mytable values (7,8,'15-OCT-2006');
I'm trying to select the rec_num, status_num, and status_date for the max date for each individual rec_num... it basically tells me the current status of each individual record by getting the status for the most recent date... like the following:
rec_num, status_num, date
1, 3, 15-SEP-2006
2, 2, 17-AUG-2006
3, 4, 07-SEP-2006
etc
This query works... it gets me the max date for each record... but it doesn't give me the status_num:
select rec_num, max(status_date)
from mytable
group by rec_num
Adding status_num messes it up... I know I need some kindof sub-query, but haven't been able to get one to work.
I'd also like a query to get a count on how many records currently exist in each status.
Can someone help me out? Oracle 8i. Thanks!

Answer 1

SQL> select * from my_table;
   REC_NUM STATUS_NUM STATUS_DA
         1          1 01-AUG-06
         1          2 14-AUG-06
         1          8 01-SEP-06
         1          3 15-SEP-06
         1          2 03-SEP-06
         2          2 17-AUG-06
         3          2 02-SEP-06
         3          4 07-SEP-06
         4          1 18-SEP-06
         4          4 27-SEP-06
         4          2 18-SEP-06
         5          1 01-OCT-06
         5          2 03-OCT-06
         5          3 05-OCT-06
         6          1 01-OCT-06
         7          2 14-OCT-06
         7          8 15-OCT-06
SQL> select mt.rec_num,
  2         mt.status_num,
  3         mt.status_date
  4    from (select row_number() over (partition by rec_num order by status_date desc) rn,
  5                 rec_num,
  6                 status_num,
  7                 status_date
  8            from my_table) mt
  9   where mt.rn = 1;
   REC_NUM STATUS_NUM STATUS_DA
         1          3 15-SEP-06
         2          2 17-AUG-06
         3          4 07-SEP-06
         4          4 27-SEP-06
         5          3 05-OCT-06
         6          1 01-OCT-06
         7          8 15-OCT-06
7 rows selected.
SQL>