How to distribute sales with partitions - sql

Question

I have 2 tables:
1st table columns: ItemCode int, Amount float (I have over 1000 ItemCodes)
2nd table columns: ItemCode int, SoldAmount float, Price float (I have over 10000 sale rows for different items)
Example:
ItemId 1528's Amount in 1st table is 244. That items sales in the 2nd table is as below:
Sale 1 Amount = 120, Price = 10
Sale 2 Amount = 120, Price = 30
Sale 3 Amount = 100, Price = 20
Sale 4 Amount = 10, Price = 25
ItemCode
Amount
1528
244
1530
150
ItemCode
Date
Amount
Price
1528
2021.11.01
120
10
1530
2021.10.01
120
30
1528
2021.09.01
100
20
1530
2021.08.01
10
25
Tried cursor and loop , but no desired output.
The desired outcome is to distribute that 100 amount with the sales above like following:
Sale 1 Amount 60: 100 - 60 = 40 with price 5 --- So we continue to the next row and subtract whatever is left
Sale 2 Amount 30: 40 - 30 = 10 with price 6 --- So we continue to the next row and subtract whatever is left
Sale 3 Amount 20: 10 - 20 = -10 with price 7 --- So we stop here as the amount is equal to 0 or below .
As the result we should get this:
60 * 5 = 300
30 * 6 = 180
10 * 7 = 70 (that 10 is derived from whatever could be subtracted before it hits 0)
Desired table as below
ItemCode
Date
Amount
Price
1528
2021.11.01
120
10
1528
2021.10.01
120
30
1528
2021.09.01
4
20
My last attempt was as below
WITH CTE AS (
SELECT ItemCode, SUM(Amount) AS Amount
FROM table 1
GROUP BY STOCKREF )
SELECT *,
IIF(LAG(table1.Amount - table2.amount) OVER (PARTITION BY table1.Amount ORDER BY Date DESC) IS NULL, table1.Amount - table2.amount,
LAG(table1.Amount - table2.amount) OVER (PARTITION BY CTE.ItemCode ORDER BY Date DESC) - table2.AMOUNT) AS COL
FROM CTE JOIN (SELECT ItemCode, DATE_, AMOUNT, PRICE FROM table2) table 2 ON table1.ItemCode = table2.Amount

Answer 1

Hopefully this addresses the right question - if you're trying to create a running total per item_code, deducting the sale quantity from starting inventory from first-to-last sale, maybe this would work:
CREATE TABLE #items (item_code INT,
item_amount INT);
INSERT INTO #items (item_code, item_amount)
VALUES (1528, 244);
INSERT INTO #items (item_code, item_amount)
VALUES (1529, 240);
CREATE TABLE #sales (item_code INT,
sale_date DATE,
sale_amount INT,
sale_price DECIMAL(12,2));
INSERT INTO #sales (item_code, sale_date, sale_amount, sale_price)
VALUES (1528, '2021-12-01', 50, 5);
INSERT INTO #sales (item_code, sale_date, sale_amount, sale_price)
VALUES (1528, '2021-11-29', 120, 6.76292);
INSERT INTO #sales (item_code, sale_date, sale_amount, sale_price)
VALUES (1528, '2021-11-15', 120, 6.6453);
INSERT INTO #sales (item_code, sale_date, sale_amount, sale_price)
VALUES (1528, '2021-11-01', 100, 6.96875);
INSERT INTO #sales (item_code, sale_date, sale_amount, sale_price)
VALUES (1529, '2021-11-30', 48, 7.2);
INSERT INTO #sales (item_code, sale_date, sale_amount, sale_price)
VALUES (1529, '2021-11-18', 48, 3.5);
INSERT INTO #sales (item_code, sale_date, sale_amount, sale_price)
VALUES (1529, '2021-11-09', 96, 3.9);
INSERT INTO #sales (item_code, sale_date, sale_amount, sale_price)
VALUES (1529, '2021-11-05', 96, 3.75);
;WITH all_sales_with_running_totals AS ( --Calculate the running total of each item, deducting sale amount from total starting amount, in order of first sale to last
SELECT s.item_code,
s.sale_date,
s.sale_price,
i.item_amount AS starting_amount,
s.sale_amount,
i.item_amount - SUM(sale_amount) OVER(PARTITION BY s.item_code
ORDER BY s.sale_date
ROWS UNBOUNDED PRECEDING
) AS running_sale_amount
FROM #sales AS s
JOIN #items AS i ON s.item_code = i.item_code
),
sales_with_prev_running_total AS ( --Add the previous rows' running total, to assist with the final calculation
SELECT item_code,
sale_date,
sale_price,
starting_amount,
sale_amount,
running_sale_amount,
LAG(running_sale_amount, 1, NULL) OVER(PARTITION BY item_code
ORDER BY sale_date
)AS prev_running_sale_amount
FROM all_sales_with_running_totals
)
SELECT item_code, --Return the final running sale amount for each sale - if the inventory has already run out, return null. If there is insufficient inventory to fill the order, fill it with the qty remaining. Otherwise, fill the entire order.
sale_date,
sale_price,
starting_amount,
sale_amount,
running_sale_amount,
prev_running_sale_amount,
CASE WHEN prev_running_sale_amount <= 0
THEN NULL
WHEN running_sale_amount < 0
THEN prev_running_sale_amount
ELSE sale_amount
END AS result_sale_amount
FROM sales_with_prev_running_total;