Re: [GENERAL] SQL Question

[Alex]

Julian Scarfe wrote:

From: "Alex" <[EMAIL PROTECTED]>

- 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

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Thanks for the help. will give it a try.

Alex

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