RE: tricky group by questions

Also your query is doing:

> to_date('20071125 1500', 'yyyymmdd hh24mi')
AND
< to_date('20071125 1600', 'yyyymmdd hh24mi')

If your intervals in your table are 1 hour intervals, this will never
return any data (assuming your 1 hour intervals occur on the hour).

Now if you were using a 'BETWEEN to_date(xx) and to_date(yy)' then it
would include both 1500 and 1600.  But your excluding them with a '>'.
You could of course do a '>=' and a '<=' to include the 1500 and 1600.



Chris Taylor
Sr. Oracle DBA
Ingram Barge Company
Nashville, TN 37205
Office: 615-517-3355
Cell: 615-354-4799
Email: chris.taylor@xxxxxxxxxxxxxxx

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Taylor, Chris David
Sent: Tuesday, November 27, 2007 9:47 AM
To: ryan_gaffuri@xxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: RE: tricky group by questions

Unless I'm mistaken, a group by will not ignore those rows especially
when using a count(*).

Either something else is disqualifying those rows from returning, or you
might have a corrupt index if it is doing an index scan.

Also, your results don't match your query.  Looks like you're looking
for 11/11/2007 dates but you're limiting it to dates > 11/25/2007.  I
assume this was just an oversight.



Chris Taylor
Sr. Oracle DBA
Ingram Barge Company
Nashville, TN 37205
Office: 615-517-3355
Cell: 615-354-4799
Email: chris.taylor@xxxxxxxxxxxxxxx

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of
ryan_gaffuri@xxxxxxxxxxx
Sent: Tuesday, November 27, 2007 9:31 AM
To: oracle-l@xxxxxxxxxxxxx
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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