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Re: SQL Query

From: Mark Wimer <mwimer(at)usgs(dot)gov>
To: Ashish Karalkar <ashish_postgre(at)yahoo(dot)co(dot)in>
Cc: ashish(dot)karalkar(at)netcore(dot)co(dot)in,pgsql-novice(at)postgresql(dot)org
Subject: Re: SQL Query
Date: 2007-12-13 17:23:39
Message-ID: OF27C227F3.63C28F73-ON852573B0.005F68AC-852573B0.005F8CEF@usgs.gov (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-novice
See if this works; the max aggregate in the subquery could be just about 
any function, since it's only going to join to one row. 



select max(m1.output_date), m1.parent_id, max(m2.output_id) as 
latest_output
from my_table M1 inner join (select output_date, output_id, parent_ID from 
my_table) as M2
        on m1.output_date = m2.output_date and m1.parent_ID = m2.parent_ID 

Where M1.output_date < now()
Group by m1.parent_id


-- Mark





Ashish Karalkar <ashish_postgre(at)yahoo(dot)co(dot)in> 
Sent by: pgsql-novice-owner(at)postgresql(dot)org
12/13/2007 04:47 AM

To
pgsql-novice(at)postgresql(dot)org, ashish(dot)karalkar(at)netcore(dot)co(dot)in
cc

Subject
[NOVICE] SQL Query






Hello List member,
I have a table which ha sfollowing structure

my_table:
(
    output_id serial priimary key,
    parent_id int,
    output_date timesatmp
)

parent_table:

(parent_id int,
parent desc
)

the my_table contains data for previous as well as future output dates.
for single parent there may be multiple rows.

I want to retrieve all the output_id  which are having latest output_date 
but less than now() (no future output_dates) group by  parent_id 

Thanks in advance

With Regards
Ashish...












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