Access join on first record - sql

Question

I have two tables in an Access database, tblProducts and tblProductGroups.
I am trying to run a query that joins both of these tables, and brings back a single record for each product. The problem is that the current design allows for a product to be listed in the tblProductGroups table more than 1 - i.e. a product can be a member of more than one group (i didnt design this!)
The query is this:
select tblProducts.intID, tblProducts.strTitle, tblProductGroups.intGroup
from tblProducts
inner join tblProductGroups on tblProducts.intID = tblProductGroups.intProduct
where tblProductGroups.intGroup = 56
and tblProducts.blnActive
order by tblProducts.intSort asc, tblProducts.curPrice asc
At the moment this returns results such as:
intID | strTitle | intGroup
1 | Product 1 | 1
1 | Product 1 | 2
2 | Product 2 | 1
2 | Product 2 | 2
Whereas I only want the join to be based on the first matching record, so that would return:
intID | strTitle | intGroup
1 | Product 1 | 1
2 | Product 2 | 1
Is this possible in Access?
Thanks in advance
Al

Answer 1

This option runs a subquery to find the minimum intGoup for each tblProducts.intID.
SELECT tblProducts.intID
, tblProducts.strTitle
, (SELECT TOP 1 intGroup
FROM tblProductGroups
WHERE intProduct=tblProducts.intID
ORDER BY intGroup ASC) AS intGroup
FROM tblProducts
WHERE tblProducts.blnActive
ORDER BY tblProducts.intSort ASC, tblProducts.curPrice ASC

Answer 2

This works for me. Maybe this helps someone:
SELECT
a.Lagerort_ID,
FIRST(a.Regal) AS frstRegal,
FIRST(a.Fachboden) AS frstFachboden,
FIRST(a.xOffset) AS frstxOffset,
FIRST(a.yOffset) AS frstyOffset,
FIRST(a.xSize) AS frstxSize,
FIRST(a.ySize) AS frstySize,
FIRST(a.Platzgr) AS frstyPlatzgr,
FIRST(b.Artikel_ID) AS frstArtikel_ID,
FIRST(b.Menge) AS frstMenge,
FIRST(c.Breite) AS frstBreite,
FIRST(c.Tiefe) AS frstTiefe,
FIRST(a.Fachboden_ID) AS frstFachboden_ID,
FIRST(b.BewegungsDatum) AS frstBewegungsDatum,
FIRST(b.ErzeugungsDatum) AS frstErzeugungsDatum
FROM ((Lagerort AS a)
LEFT JOIN LO_zu_ART AS b ON a.Lagerort_ID = b.Lagerort_ID)
LEFT JOIN Regal AS c ON a.Regal = c.Regal
GROUP BY a.Lagerort_ID
ORDER BY FIRST(a.Regal), FIRST(a.Fachboden), FIRST(a.xOffset), FIRST(a.yOffset);
I have non unique entries for Lagerort_ID on the table LO_zu_ART. My goal was to only use the first found entry from LO_zu_ART to match into Lagerort.
The trick is to use FIRST() an any column but the grouped one. This may also work with MIN() or MAX(), but I have not tested it.
Also make sure to call the Fields with the "AS" statement different than the original field. I used frstFIELDNAME. This is important, otherwise I got errors.

Answer 3

Create a new query, qryFirstGroupPerProduct:
SELECT intProduct, Min(intGroup) AS lowest_group
FROM tblProductGroups
GROUP BY intProduct;
Then JOIN qryFirstGroupPerProduct (instead of tblProductsGroups) to tblProducts.
Or you could do it as a subquery instead of a separate saved query, if you prefer.

Answer 4

It's not very optimal, but if you're bringing in a few thousand records this will work:
Create a query that gets the max of tblProducts.intID from one table and call it qry_Temp.
Create another query and join qry_temp to the table you are trying to join against, and you should get your results.