Friday, March 23, 2012

Query for most recent of duplicate records

I need some ideas on this query.
I have a table with entries similar to the following with columns name,
id, and timestamp.
kmyoung 345 2005-08-22 07:29:00.000
kmyoung 345 2005-08-29 07:29:15.000
mphillips 360 2005-08-27 14:48:18.000
rbeheler 360 2005-08-22 09:29:11.000
rbeheler 360 2005-08-24 09:28:19.000
rbeheler 360 2005-08-29 09:27:54.000
I need a resultant set that gives me the records with the most recent
timestamp for each ID as listed below.
kmyoung 345 2005-08-29 07:29:15.000
rbeheler 360 2005-08-29 09:27:54.000
Thanks for the help.Try,
select
*
from
t1 as a
where
c3 = (select max(b.c3) from t1 as b where b.[id] = a.[id])
go
AMB
"Jeff" wrote:

> I need some ideas on this query.
> I have a table with entries similar to the following with columns name,
> id, and timestamp.
> kmyoung 345 2005-08-22 07:29:00.000
> kmyoung 345 2005-08-29 07:29:15.000
> mphillips 360 2005-08-27 14:48:18.000
> rbeheler 360 2005-08-22 09:29:11.000
> rbeheler 360 2005-08-24 09:28:19.000
> rbeheler 360 2005-08-29 09:27:54.000
> I need a resultant set that gives me the records with the most recent
> timestamp for each ID as listed below.
> kmyoung 345 2005-08-29 07:29:15.000
> rbeheler 360 2005-08-29 09:27:54.000
> Thanks for the help.
>|||select name, id, max(timestamp) as timestamp
from thetable
group by name, id
having count(*)>1 -- if you need just the ones that have dupes, add this
line
Jeff wrote:
> I need some ideas on this query.
> I have a table with entries similar to the following with columns name,
> id, and timestamp.
> kmyoung 345 2005-08-22 07:29:00.000
> kmyoung 345 2005-08-29 07:29:15.000
> mphillips 360 2005-08-27 14:48:18.000
> rbeheler 360 2005-08-22 09:29:11.000
> rbeheler 360 2005-08-24 09:28:19.000
> rbeheler 360 2005-08-29 09:27:54.000
> I need a resultant set that gives me the records with the most recent
> timestamp for each ID as listed below.
> kmyoung 345 2005-08-29 07:29:15.000
> rbeheler 360 2005-08-29 09:27:54.000
> Thanks for the help.
>|||It worked great as long as t1 was an actual table. But in actuality t1 is a
union of two tables. When I substitute (select * from t1 union select * fro
m
t2) as t1, it no longer works. Would it be possible to rewrite this with a
subquery instead of t1?
"Alejandro Mesa" wrote:
> Try,
> select
> *
> from
> t1 as a
> where
> c3 = (select max(b.c3) from t1 as b where b.[id] = a.[id])
> go
>
> AMB
> "Jeff" wrote:
>|||Very close, but I ended up with this resultant set instead.
kmyoung 345 2005-08-29 07:29:15.000
mphillips 360 2005-08-27 14:48:18.000
rbeheler 360 2005-08-29 09:27:54.000
I ended up with two entries for id 360.
"Trey Walpole" wrote:

> select name, id, max(timestamp) as timestamp
> from thetable
> group by name, id
> having count(*)>1 -- if you need just the ones that have dupes, add this
> line
>
> Jeff wrote:
>|||Nevermind. It worked fine by simply substituting the subquery in place of
t1. Works exactly as I need it to .
Thanks!
"Jeff" wrote:
> It worked great as long as t1 was an actual table. But in actuality t1 is
a
> union of two tables. When I substitute (select * from t1 union select * f
rom
> t2) as t1, it no longer works. Would it be possible to rewrite this with
a
> subquery instead of t1?
> "Alejandro Mesa" wrote:
>|||oops - seeing a little cross-eyed today...
Jeff wrote:
> Very close, but I ended up with this resultant set instead.
> kmyoung 345 2005-08-29 07:29:15.000
> mphillips 360 2005-08-27 14:48:18.000
> rbeheler 360 2005-08-29 09:27:54.000
> I ended up with two entries for id 360.
> "Trey Walpole" wrote:
>

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