Inventory Aging Report (FIFO) - sql

Question

Have a problem to solve in the SQL Server to generate a Inventory aging report using FIFO Based on SKU & Warehouse. I have attached the schema here.
SKU
TransactionType
WarehouseCode
TransactionDate
Qty
100
IN
WH1
2021-04-30
100
100
IN
WH2
2021-04-30
50
101
IN
WH1
2021-04-30
30
101
IN
WH2
2021-05-01
25
100
OUT
WH2
2021-05-02
30
100
OUT
WH1
2021-05-02
20
100
OUT
WH1
2021-05-04
50
100
OUT
WH2
2021-05-04
20
100
OUT
WH1
2021-05-05
25
100
IN
WH2
2021-05-10
30
100
IN
WH1
2021-05-11
30
101
OUT
WH2
2021-05-12
20
100
OUT
WH1
2021-05-15
30
Based on the above schema structure, i need to develop a inventory aging report based on first in first out (FIFO) and show the remaining qty of each SKU and Warehouse combination and make the previous incoming records remaining quantities as zero.
Expected report format Assuming the report is run on (2021-05-20)
SKU
TransactionType
WarehouseCode
TransactionDate
Qty
Remaining
Aging
100
IN
WH1
2021-04-30
100
0
21
100
IN
WH2
2021-04-30
50
0
21
101
IN
WH1
2021-04-30
30
30
21
101
IN
WH2
2021-05-01
25
5
20
100
IN
WH2
2021-05-10
30
30
11
100
IN
WH1
2021-05-11
50
5
10
Thanks in advance.

Answer 1

You can use window functions to sum up the IN records over time (a cumulative sum), and find out the final total OUT.
Then, if the in_so_far is less than the final_out, you know you have use everything for that line.
The aging just appears to be a datediff() against a constant value?
WITH
cumulative AS
(
SELECT
*,
SUM(CASE WHEN TransactionType = 'IN' THEN Qty ELSE 0 END)
OVER (
PARTITION BY SKU, WarehouseCode
ORDER BY TransactionDate
)
AS qty_in_so_far,
SUM(CASE WHEN TransactionType = 'OUT' THEN Qty ELSE 0 END)
OVER (
PARTITION BY SKU, WarehouseCode
)
AS qty_out_final
FROM
inventory
)
SELECT
*,
CASE
WHEN qty_out_final > qty_in_so_far
THEN 0
WHEN qty_in_so_far - qty_out_final > qty
THEN qty
ELSE qty_in_so_far - qty_out_final
END
AS qty_final,
DATEDIFF(day, TransactionDate, '2021-05-20') + 1 AS aging
FROM
cumulative
WHERE
TransactionType = 'IN'
ORDER BY
TransactionDate,
SKU,
WarehouseCode
Demo... https://dbfiddle.uk/?rdbms=sqlserver_2019&fiddle=b6725edd625001cd874bdb8f37283763