Julian Scarfe wrote:
From: "Alex" <alex@xxxxxxxxxxxxxxx>
- How can i select only the newest record for each ProdId ?
100 | 2005-04-01 200 | 2005-04-01
DISTINCT ON was made for this and on the similar tables I have performs rather more efficiently than using a subquery.
select distinct on (ProdId) ProdId , LastUpdate from produpdate order by ProdId , LastUpdate desc;
- How can i select to retrieve the last 2 dates in record
100 | 2005-04-01 | 2005-03-01 200 | 2005-04-01 | 2005-03-01
To get the previous one, my first thought is something like:
select distinct on (ProdId) ProdId , LastUpdate from produpdate p1 where LastUpdate <> ( select max(LastUpdate ) from produpdate p2 where p2.ProdId = p1.ProdId ) order by ProdId , LastUpdate desc ;
but there may be a much more efficient way of getting the nth result in general.
Julian Scarfe
---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@xxxxxxxxxxxxxx so that your message can get through to the mailing list cleanly
Thanks for the help. will give it a try.
Alex
---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
