Ashish wants latest output_date but less than now()
>want to retrieve all the output_id which are having latest
>output_date but less than now() (no future output_dates)
The query written by Tirnath will return count of all output ids given parent id where output_date is less than now, it won't return rows for latest output_date.
I propose the following solution:
SELECT o.output_id
FROM my_table o, parent_table p
WHERE o.parent_id = p.parent_id
AND o.output_date < now()
AND NOT EXISTS
(
SELECT out.output_date
FROM my_table out
WHERE out.parent_id = o.parent_id
AND out.output_date < now ()
AND o.output_date < out.output_date
);
The idea is get first maximum date which is less than now(). Assuming now() as the maximum date, the problem reduces to finding second maximum date.
The nested query means: the date in context (outer query date) shouldn't be less than any date which is less than now().
This will give you the latest output date grouped by parent_id albeit there's no group clause used. :-)
Let me know if there's any mistake.
Cheers,
Ranbeer Makin
On Dec 13, 2007 6:32 PM, Trinath Somanchi <trinaths@xxxxxxxxxx
> wrote:
Hi ,
Try this out
SELECT count( o.id)
FROM output_table o , parent_table p
WHERE o.pid=p.pid AND o_date < now()
GROUP BY p.pid ;--
On Thu, 13 Dec 2007 10:00:56 +0000 (GMT)
Ashish Karalkar < ashish_postgre@xxxxxxxxxxx> wrote:
> 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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Trinath Somanchi ,
(trinaths@xxxxxxxxxx),
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