MAX for each subset

I have a table that looks like this:

+---------------------------------------------+
| EVENT_ID | ITEM_ID | PERSON_ID | EVENT_DATE |
+---------------------------------------------+
| 123      | 1       | 2         | 21-AUG-03  |
| 124      | 1       | 3         | 22-AUG-03  |
| 125      | 1       | 45        | 23-AUG-03  |
| 126      | 1       | (null)    | 24-AUG-03  |
| 127      | 2       | 2         | 25-AUG-03  |
| 128      | 2       | 6         | 26-AUG-03  |
| 129      | 2       | 1         | 27-AUG-03  |
+---------------------------------------------+

So, I need to get the latest (MAX(event_date)), non-null person_id per item_id. We have come up with a fairly simple PL/SQL approach to this, but were trying to get the job done with straight SQL. Anyone have an idea?

Just as a side-note, the event_id will not always be sequential like this. We have two redundant DB servers.

Thanks ahead of time.

The following requires only one full table scan.

SELECT Item_ID, Person_ID, Event_Date FROM
(
   SELECT Event_ID, Person_ID, Item_ID, Event_Date
      , MAX(EVENT_DATE) OVER (PARTITION BY Item_ID) HighEventDate 
   FROM Event_Table WHERE Person_ID IS NOT NULL
)
WHERE Event_Date = HighEventDate;

StackExchange Database Administrators Q#2361, answer score: 7