getting duplicate records in Access query - sql

Question

I have three tables: The [inventory snapshot] table shows the name of the product and how many we have on site; the [inbound loads] table shows how many are coming in; the [outbound routes] table lists how many are going out.
I was getting unique values when I only had the first and second table (showing on-hand and 'arriving') but when I added in the third, I began getting multiple records instead of summed records.
Purpose of query
I work in a warehouse and I'm trying to isolate pick slots that are 1) low on inventory; 2)have no more product coming in; 3) I'd like to know if there are open orders to ship out any of the remaining product.
SELECT DISTINCT [inventory snapshot].locn_brcd,
[inventory snapshot].description,
[inventory snapshot].item_name,
Sum([inventory snapshot].on_hand_qty) AS SumOfON_HAND_QTY,
Sum([outbound routes].quantity) AS SumOfQuantity
FROM [outbound routes]
RIGHT JOIN ([inbound loads]
RIGHT JOIN [inventory snapshot]
ON [inbound loads].[wrin number] =
[inventory snapshot].item_name)
ON [outbound routes].[wrin number] =
[inventory snapshot].item_name
GROUP BY [inventory snapshot].locn_brcd,
[inventory snapshot].description,
[inventory snapshot].item_name,
[inbound loads].[quantity to receive]
HAVING ( ( ( Sum([inventory snapshot].on_hand_qty) ) < 10 )
AND ( ( [inbound loads].[quantity to receive] ) IS NULL ) );

Answer 1

Since you resolved your issue, consider further adjustment of grouping columns. Right now, the GROUP BY clause contains one more field than SELECT clause, namely: [inbound loads].[quantity to receive].
Typically, in aggregate SQL queries like this one, numeric values like quantity are not grouped but run as aggregated columns. You may have added it to GROUP BY in order to use it in HAVING. However, non-aggregates can be handled in WHERE to filter before aggregation. (Oddly, MS Access tends to move such level filtering in HAVING using Query Design.)
Consider below refactored SQL which uses table alias to avoid repetition of long table names. Of course, remove your needless location grouping.
SELECT s.locn_brcd
, s.description
, s.item_name
, SUM(s.on_hand_qty) AS SumOfON_HAND_QTY
, SUM(r.quantity) AS SumOfQuantity
FROM [outbound routes] r
RIGHT JOIN ([inbound loads] l
RIGHT JOIN [inventory snapshot] s
ON l.[wrin number] = s.item_name)
ON r.[wrin number] = s.item_name
WHERE l.[quantity to receive] IS NULL
GROUP BY s.locn_brcd
, s.description
, s.item_name
HAVING SUM(s.on_hand_qty) < 10 ;
By the way, the SQL industry tends to use LEFT JOIN rather than RIGHT JOIN for readability which you may not have control as this query may be output from Query Design. Try equivalent version without nesting JOINs where parentheses is required in Access SQL:
FROM ([inventory snapshot] s
LEFT JOIN ([inbound loads] l
ON l.[wrin number] = s.item_name)
LEFT JOIN [outbound routes] r
ON r.[wrin number] = s.item_name