Subselect on date - sql

Question

In an Access database there are two tables.
Table one containing Articles and table two contains Prices.
So Articles is the description of all articles and the prices
table just contains an article number, a date date and a price.
If a prices changes, there will be added a new row to prices.
The prices have a date from which on that price shall be used.
Now I want to get the prices that were valid on 01. Oct 2012.
I used my query on current prices and added and prsdat<#02/10/2012#
to the subselect in the query.
Here is what I already have:
SELECT
Articles.ARTNR,
Articles.TXT,
Articles.ACTIVE,
Prices.PRICE,
Prices.PRSGR,
Prices.PRSDAT
FROM
Articles INNER JOIN Prices ON Articles.ARTNR = Prices.ARTNR
WHERE
(((Articles.ACTIVE)="Y") AND
((Prices.PRSGR)=0) AND
((Prices.PRSDAT)=
(SELECT
max(prsdat)
FROM
Prices as art
WHERE
art.artnr = Prices.artnr and prsdat<#02/10/2012#)))
ORDER BY
Articles.ARTNR;
Now the select returns articles that I did not see with this select
I used before, having just added and prsdat<#01/10/2012#.
The result is now 430 articles, before I just had about 260.
The prices returned are older, but I'm not sure about the date format.
In the table I see DD.MM.YYYY, and in the query i shall use MM/DD/YYYY or DD/MM/YYYY?
What is the correct form of this select?

Answer 1

SELECT
a.ARTNR
, a.TXT
, a.ACTIVE -- dubious, since it is constant
, p.PRICE
, p.PRSGR -- dubious, since it is constant
, p.PRSDAT
FROM Articles a
INNER JOIN Prices p ON a.ARTNR = p.ARTNR
WHERE a.ACTIVE = 'Y'
AND p.PRSGR = 0
AND p.prsdat < #02/10/2012#
AND NOT EXISTS (
SELECT *
FROM Prices nx
WHERE nx.ARTNR = p.ARTNR
AND nx.PRSGR = 0
AND nx.prsdat < #02/10/2012#
AND nx.prsdat > p.prsdat
)
ORDER BY
Articles.ARTNR
;