これでうまくいきます:
SQL> select id, other_id, date_value, value, cnt from
2 (
3 SELECT id, other_id, date_value, value,
4 case
5 when other_id is null or other_id = '0' then 1
6 else ROW_NUMBER() OVER (partition by other_id order BY Date_Value desc)
7 end r,
8 case
9 when other_id is null or other_id = '0' then 1
10 else count(*) OVER (partition by other_id)
11 end cnt
12 FROM some_table
13 )
14 where r = 1
15 order by id;
ID OTH DATE_VALUE VALUE CNT
---------- --- ------------------- ---------- ----------
1 abc 2011-04-20 21:03:05 104 3
3 xyz 2011-04-20 21:03:03 130 2
5 0 2011-04-20 21:02:08 65 1
7 2011-04-20 21:02:07 200 1
8 0 2011-04-20 21:02:07 201 1
9 2011-04-20 21:02:07 202 1
6 rows selected.
SQL>