select my_sub.max_date, broadcast_history.status
from (
SELECT MAX(date_sent) max_date, broadcast_id
FROM broadcast_history
GROUP BY broadcast_id
) my_sub
inner join broadcast_history on (
broadcast_history.broadcast_id = my_sub.broadcast_id
and broadcast_history.date_sent = my_sub.max_date
);
This should work if the combined broadcast_id, date_sent is unique. If not, you will need to decide what record to pick in case of a tie.
On 6/1/06, Collin Peters <cadiolis@gmail.com> wrote: I am having some serious mental block here. Here is the abstract
version of my problem. I have a table like this:
unique_id (PK) broadcast_id date_sent status
1 1 2005-04-04 30
2 1 2005-04-01 30
3 1 2005-05-20 10
4 2 2005-05-29 30
So it is a table that stores broadcasts including the broadcast_id,
the date sent, and the status of the broadcast.
What I would like to do is simply get the last date_sent and it's
status for every broadcast. I can't do a GROUP BY because I can't put
an aggregate on the status column.
SELECT MAX(date_sent), status
FROM broadcast_history
GROUP BY broadcast_id
How do I get the status for the most recent date_sent using GROUP BY?
DISTINCT also doesn't work
SELECT DISTINCT ON (email_broadcast_id) *
FROM email_broadcast_history
ORDER BY date_sent
As you have to have the DISTINCT fields matching the ORDER BY fields.
I have to ORDER BY date_sent, but I can't do a DISTINCT on date_sent
I keep thinking am I missing something. Does anybody have any ideas?
---------------------------(end of broadcast)---------------------------
TIP 2: Don't 'kill -9' the postmaster
--
==================================================================
Aaron Bono
President Aranya Software Technologies, Inc.
http://www.aranya.com We take care of your technology needs.
Phone: (816) 695-6071
==================================================================
