RE: tricky group by questions

Ryan,

Here's a nice AskTom example, which I think will do exactly what you want: http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:8912311513313

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Mark J. Bobak
Senior Database Administrator, System & Product Technologies ProQuest
789 E. Eisenhower, Parkway, P.O. Box 1346 Ann Arbor MI 48106-1346
+1.734.997.4059  or +1.800.521.0600 x 4059 mark.bobak_at_il.proquest.com
www.proquest.com
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ProQuest...Start here.

-----Original Message-----

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of ryan_gaffuri_at_comcast.net Sent: Tuesday, November 27, 2007 10:31 AM To: oracle-l_at_freelists.org
Subject: tricky group by questions

I am writing a query that is grouping by 1 hour blocks over a period of time as follows

I am pretty sure the answer involves using "where not exists", but I can't get the dates I want to return.

select to_char(mydate, 'yyyymmdd hh24') , count(*) from mytab
where mydate < sysdate
and mydate > to_date('20071125 1500', 'yyyymmdd hh24mi')

and mydatedate < to_date('20071125 1600', 'yyyymmdd hh24mi')
group by to_char(mydate, 'yyyymmdd hh24')
order by to_char(mydate, 'yyyymmdd hh24') desc

Now I have one hour periods that do not have any rows. A standard group by just ignores those periods. I want periods with no data to return and have a count(*) = 0

so I would have

2007111101 20
2007111102 0
2007111103 10

now it returns as

2007111101 20
2007111103 10
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http://www.freelists.org/webpage/oracle-l Received on Tue Nov 27 2007 - 10:28:49 CST