RE: trouble with sql

this does yield a somewhat better execution plan.
 
i was just thinking there was some way (possibly/probably through
analytics) to pull the value of column 4 without having to do a self
join.
 
thanks for the help!
chris
 
 

________________________________

From: Boyle, Christopher [mailto:Christopher.Boyle@xxxxxxxxxxxxx] 
Sent: Wednesday, January 03, 2007 3:33 PM
To: Stephens, Chris; oracle-l@xxxxxxxxxxxxx
Subject: RE: trouble with sql



Okay, this might have a better explain plan  (assuming 9i or above)

 

with ps2 as ( select/*+ materialize */ p.periodID, ps.projectNumber,
max(ps.changeDate) as changeDate

 from period p, projectStatus ps

 where ps.changeDate >= trunc( p.startDate )

       and trunc( ps.changeDate ) <= p.endDate

 group by p.periodID, ps.projectNumber )

 select ps2.periodID, ps2.projectNumber, ps2.changeDate, ps3.statusID

 from ps2, projectStatus ps3

where ps2.projectNumber = ps3.projectNumber and ps2.changeDate =
ps3.changeDate;

 

but I cant tell without table definitions.  Can a project have more than
one active status?  From the query I would guess that the max change
date indicates the current status but I am not sure.  Can periods
overlap?  

 

Chris

 

________________________________

From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Stephens, Chris
Sent: Wednesday, January 03, 2007 3:34 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: trouble with sql

 

There has got to be a way to do this but I can't find the syntax. 

 

Essentially I need the max of column 3 grouped by column 1 and 2 and
also the value of column 4 that corresponds to the returned columns 1,2,
and 3.

 

Here is the actual sql that I believe to be using an unnecessary join:

select ps2.periodID, ps2.projectNumber, ps2.changeDate, ps3.statusID
from ( select p.periodID, ps.projectNumber, max(ps.changeDate) as
changeDate
 from period p, projectStatus ps
 where ps.changeDate >= trunc( p.startDate )
       and trunc( ps.changeDate ) <= p.endDate
 group by p.periodID, ps.projectNumber ) ps2, projectStatus ps3
where ps2.projectNumber = ps3.projectNumber and ps2.changeDate =
ps3.changeDate

 

Is there a better way to write this?

 


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