Hello
Here a suggestion for your problem.
SELECT a.id AS t1_id, d.id AS t2_id, d.somedate AS t2_somedate
FROM t1 a
JOIN ( SELECT id, t1id, somedate FROM t2 b WHERE (t1id, somedate) IN ( SELECT t1id, somedate
FROMt2 c WHERE c.t1id = b.t1id ORDER BY somedate DESC LIMIT 1 ) ) d
ON (a.id=d.t1id);
t1_id | t2_id | t2_somedate
-------+-------+------------- 1 | 3 | 2010-05-25 2 | 5 | 2010-05-26
(2 rows)
Hope this helps
Regards (Saluti da Zurigo)
Luigi Antognini
-----Original Message-----
From: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org]
On Behalf Of Michele Petrazzo - Unipex
Sent: Wednesday, May 26, 2010 7:35 PM
To: pgsql-sql@postgresql.org
Subject: [SQL] inner join and limit
Hi list,
I have two table that are so represented:
t1:
id int primary key
... other
t2:
id int primary key
t1id int fk(t1.id)
somedate date
... other
data t1:
1 | abcde
2 | fghi
data t2:
1 | 1 | 2010-05-23
2 | 1 | 2010-05-24
3 | 1 | 2010-05-25
4 | 2 | 2010-05-22
5 | 2 | 2010-05-26
I'm trying to create a query where the data replied are:
join t1 with t2 and return only the LIMIT 1 (or N) of the t2, with date
order (of t2).
Data should be:
t1.id | t2.id | t2,somedate
1 | 3 | 2010-05-25
2 | 5 | 2010-05-26
As said, I'm trying, but without success...
Can be done for you?
Thanks,
Michele
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