LEFT JOIN in Query returning more records than desired - sql

Question

I'm working on an MS ACCESS query which should pull all available data from one main table (specified by FROM) and then joining three additional tables via LEFT JOIN. My issue is that the query is returning more records because of a one to many relationship.
Is there any way I can return only ONE record per line in the main table? Any help is greatly appreciated!! Thank you!
SELECT tbl_Item_PO.Item,
tbl_ItemSKUType.SKU,
tbl_Item_PO.[EX-FACTORY DATE],
tbl_Item_PO.[QTY PER SHIPMENT],
IIf(tbl_Item_PO.Item=Posted_Inv_Tran.Item And tbl_Item_PO.Whse=Posted_Inv_Tran.Whse And tbl_Item_PO.[ITR#]=Posted_Inv_Tran.[TRN Number],0,tbl_Item_PO.[QTY PER SHIPMENT]) AS QTY,
tbl_Item_PO.WHSE, tbl_WhseRegion.Region
FROM ((tbl_Item_PO
LEFT JOIN tbl_ItemSKUType ON tbl_Item_PO.item = tbl_ItemSKUType.Item)
LEFT JOIN tbl_WhseRegion ON tbl_Item_PO.WHSE = tbl_WhseRegion.Whse)
LEFT JOIN Posted_Inv_Tran ON (tbl_Item_PO.[ITR#] = Posted_Inv_Tran.[TRN Number]) AND (tbl_Item_PO.Whse = Posted_Inv_Tran.Whse) AND (tbl_Item_PO.Item = Posted_Inv_Tran.Item);
I've also tried creating sub-queries within the join statements that return only ONE record but I cannot get that to work either:
SELECT po.Item,
ist.SKU,
po.[EX-FACTORY DATE],
po.[QTY PER SHIPMENT],
IIf(po.Item=itr.Item And po.Whse=itr.Whse And po.[ITR#]=itr.[TRN Number],0,po.[QTY PER SHIPMENT]) AS QTY,
po.WHSE,
wh.Region
FROM ((tbl_Item_PO po
LEFT JOIN (select top 1 * from tbl_ItemSKUType
RIGHT JOIN tbl_Item_PO on tbl_ItemSKUType.Item = tbl_Item_PO.item
WHERE tbl_Item_PO.Item = tbl_ItemSKUType.Item)
ist ON po.item = ist.Item)
LEFT JOIN (select top 1 * from tbl_WhseRegion
RIGHT JOIN tbl_Item_PO on tbl_WhseRegion.Whse = tbl_Item_PO.Whse
WHERE tbl_Item_PO.whse = tbl_WhseRegion.Whse)
wh ON po.Whse = wh.Whse)
LEFT JOIN (select top 1 * from Posted_Inv_Tran
RIGHT JOIN tbl_Item_PO on Posted_Inv_Tran.[TRN Number] = tbl_Item_PO.[ITR#] AND Posted_Inv_Tran.Whse = tbl_Item_PO.Whse AND Posted_Inv_Tran.Item = tbl_Item_PO.Item
WHERE (tbl_Item_PO.[ITR#] = Posted_Inv_Tran.[TRN Number]) AND (tbl_Item_PO.Whse = Posted_Inv_Tran.Whse) AND (tbl_Item_PO.Item = Posted_Inv_Tran.Item))
it ON (po.[ITR#] = it.[TRN Number]) AND (po.Whse = it.Whse) AND (po.Item = it.Item);

Answer 1

You can achieve that with a group by clause. Make sure to list all fields in that clause which identify a line, and that all other expressions/fields you have in the select clause are aggregated with some aggregation function, like Min().
NB: Your IIf condition does not need to check all those fields, just one is enough: when one matches, all will match:
SELECT tbl_Item_PO.Item,
Min(tbl_ItemSKUType.SKU) AS SKU,
tbl_Item_PO.[EX-FACTORY DATE],
tbl_Item_PO.[QTY PER SHIPMENT],
Min(IIf(tbl_Item_PO.Item=Posted_Inv_Tran.Item, 0,
tbl_Item_PO.[QTY PER SHIPMENT])) AS QTY,
tbl_Item_PO.WHSE,
Min(tbl_WhseRegion.Region) AS Region
FROM ((tbl_Item_PO
LEFT JOIN tbl_ItemSKUType
ON tbl_Item_PO.item = tbl_ItemSKUType.Item)
LEFT JOIN tbl_WhseRegion
ON tbl_Item_PO.WHSE = tbl_WhseRegion.Whse)
LEFT JOIN Posted_Inv_Tran
ON (tbl_Item_PO.[ITR#] = Posted_Inv_Tran.[TRN Number])
AND (tbl_Item_PO.Whse = Posted_Inv_Tran.Whse)
AND (tbl_Item_PO.Item = Posted_Inv_Tran.Item)
GROUP BY tbl_Item_PO.Item,
tbl_Item_PO.[EX-FACTORY DATE],
tbl_Item_PO.[QTY PER SHIPMENT],
tbl_Item_PO.WHSE;