SQL query: SUM(Quantity) - sql

Question

I'm trying to build a simple SQL query for an item availability check. My aim is to query the items whose total/summed quantity exceeds the stock level. This is what my table (simplified example) looks like:
LineNumber
Item
Quantity
StockQuantity
1
Banana
1
1
2
Apple
1
1
3
Strawberry
1
1
4
Banana
1
1
I have tried it with the following query, but it doesn't work:
SELECT
T1.[LineNumber], T1.[Item],
SUM(T1.[Quantity]), T1.[Stockquantity]
FROM
Table T1
WHERE
T1.[Quantity] > T1.[Stockquantity]
GROUP BY
T1.[LineNumber], T1.[Item], T1.[Quantity], T1.[Stockquantity]
Does anyone have any advice or tips for me on how I should do this query so that the total/summed quantities per line are compared with the stock quantity and not just the individual/single quantities per line with the stock quantity?
Thank you very much for your help in advance.

Answer 1

Given your extended information in this post: https://stackoverflow.com/a/71452446/1690217 the query you are looking for is this:
WITH TotalsLookup as (
SELECT T1.[VisOrder] as [VisOrder], T1.[U_position] as [ItemGroup-LineNumber]
, T0.[DocNum] as [DocNumber], T2.[InvntItem], T1.[ItemCode] as [Itemcode]
, T1.[Quantity], T1.[OpenCreQty] as [openQuantity]
, T2.[OnHand] as [StockQuantity]
, SUM(T1.[Quantity]) OVER (PARTITION BY T1.[ItemCode] ORDER BY T1.[VisOrder]) AS RunningTotal
FROM OQUT T0
INNER JOIN QUT1 T1 ON T0.[DocEntry] = T1.[DocEntry]
INNER JOIN OITM T2 ON T1.[ItemCode] = T2.[ItemCode]
)
SELECT VisOrder, [ItemGroup-LineNumber], DocNumber, Itemcode, Quantity, openQuantity, StockQuantity, RunningTotal
FROM TotalsLookup
WHERE DocNumber = '332050' AND [InvntItem] = 'Y' AND RunningTotal > StockQuantity
Original Post
Your example is possibly oversimplified, If StockQuantity is the result of a lookup into an inventory, so that in the example we can say the following:
Total stock on Hand of Bananas is 1
And then if you are expecting LineNumber 4 to be picked up because this line will make the SUM of Bananas greater than the total stock on hand of Bananas... then you need a Running Total of the Item records in this list:
WITH TotalsLookup as (
SELECT
T1.[LineNumber], T1.[Item],
T1.[Quantity], T1.[StockQuantity],
SUM (T1.[Quantity]) OVER (PARTITION BY Item ORDER BY LineNumber) AS RunningTotal
FROM
[Table] T1
)
SELECT *
FROM TotalsLookup
WHERE RunningTotal > StockQuantity;
LineNumber
Item
Quantity
Stockquantity
RunningTotal
4
Banana
1
1
2
See this Fiddle that covers a few variants of this query and will give you a playground to practice: http://sqlfiddle.com/#!18/a95bb/2
The origin of StockQuantity can itself have a significant impact on the performance and other query options that might be viable, I call this out so that you can be mindful of this when you apply this logic into your application domain, if StockQuantity is not a static value, but is itself an aggregate then that may impact how the comparison should be performed.

Answer 2

You can refer to aggregates of a GROUP BY in the having clause
SELECT
T1.[Item],
SUM(T1.[Quantity]) As TotalQuantity,
MAX(T1.[Stockquantity]) AS StockLevel
FROM
Table T1
GROUP BY
T1.[Item]
HAVING
SUM(T1.[Quantity]) > MAX(T1.[Stockquantity])
This assumes that the Stockquantity is the same for all occurrences of a product.
The WHERE clause is executed before grouping, the HAVING clause after grouping.
If you need the line numbers, then you can use the STRING_AGG aggregate function to join the line numbers into a single string per group
SELECT STRING_AGG(T1.[LineNumber], ', ') As LineNumbers, ...

Answer 3

your SQL modified code(SQL code didn't work) that does not provide a single output
SELECT linenumber,
a.item,
quantity,
SumQuantity,
stockquantity
FROM table A
JOIN(SELECT item,
Sum(quantity) SumQuantity,
max(stockquantity) stockquantity
FROM table C
GROUP BY item) B
ON A.item = B.item
WHERE SumQuantity> stockquantity
ouput
linenumber
item
quantity
quantity2
stockquantity
1
Banana
1
2
1
4
Banana
1
2
1
However I use the follwing query
SELECT String_agg(linenumber, ',') LineNumbers,
a.item,
quantity,
SumQuantity,
stockquantity
FROM table A
JOIN(SELECT item,
Sum(quantity) SumQuantity
max(stockquantity) stockquantity
FROM table C
GROUP BY item) B
ON A.item = B.item
WHERE SumQuantity> stockquantity
GROUP BY a.item,
quantity,
SumQuantity,
stockquantity
that bring following result
LineNumbers
Item
Quantity
SumQuantity
StockQuantity
1,4
Banana
1
2
1

Answer 4

Thank you all for your effort and suggestions for solutions. I have tried to incorporate them all. A few of them worked. With others I still have a few problems:
#Chris Schaller
I like you solution a lot! But in my non-simplified, real SQL code, there are item groups that the PARTITION function cannot cope with. My result with your solution is therefore as follows.
However, I will continue to work on it. Thanks!
WITH TotalsLookup as (
SELECT T1.[VisOrder] as 'VisOrder', T1.[U_position] as 'ItemGroup-LineNumber', T0.[DocNum] as 'DocNumber', T1.[ItemCode] as 'Itemcode', T1.[Quantity] as 'Quantity', T1.[OpenCreQty] as 'openQuantity', T2.[OnHand] as 'StockQuantity', SUM(T1.[Quantity]) OVER (PARTITION BY T1.[ItemCode] ORDER BY T1.[VisOrder]) AS RunningTotal
FROM OQUT T0
INNER JOIN QUT1 T1 ON T0.[DocEntry] = T1.[DocEntry]
INNER JOIN OITM T2 ON T1.[ItemCode] = T2.[ItemCode]
WHERE T0.[DocNum] = '332050' AND T2.[InvntItem] = 'Y'
)
SELECT *
FROM TotalsLookup
WHERE RunningTotal > Quantity
Output: here
#RF1991
I have also tried to implement your solution, but it has not really worked so far. I am still looking for the mistake. Thanks for the help!
SELECT T1.[U_position], T1.[ItemCode], T1.[Quantity], T1.[OpenCreQty], T2.[OnHand]
FROM OQUT T0
INNER JOIN QUT1 T1 ON T0.[DocEntry] = T1.[DocEntry]
INNER JOIN OITM T2 ON T1.[ItemCode] = T2.[ItemCode]
JOIN(SELECT T1.[ItemCode], SUM(T1.[Quantity]) as 'SumQuantity', MAX(T2.[OnHand]) as 'Stockquantity' FROM OQUT T0 INNER JOIN QUT1 T1 ON T0.[DocEntry] = T1.[DocEntry] INNER JOIN OITM T2 ON T1.[ItemCode] = T2.[ItemCode] GROUP BY T1.[ItemCode]) B
ON T1.[ItemCode] = B.[ItemCode]
WHERE SumQuantity > stockquantity AND T0.[DocNum] = '332050' AND T2.[InvntItem] = 'Y'
#Oliver Jacot-Descombes
It works. Thank you very much!