Running Average for stock using Recursive CTE - sql-server

Question

I have the below data and need to calculate the running average for each row using the amount from each of the previous rows.
CREATE TABLE [dbo].[AKTest](
[IntakeSellingPrice] [decimal](38, 20) NULL,
[IntakeSellingAmount] [decimal](38, 6) NULL,
[Item No_] [nvarchar](20) NOT NULL,
[Variant Code] [nvarchar](10) NOT NULL,
[Unit of Measure Code] [nvarchar](10) NOT NULL,
[Posting Date] [datetime] NOT NULL,
[PurchaseQty] [decimal](38, 20) NULL,
[ReceiptNo] [bigint] NULL,
[InventoryBalance] [decimal](38, 20) NOT NULL,
[NewBalance] [decimal](38, 20) NULL
) ON [PRIMARY]
GO
INSERT [dbo].[AKTest] ([IntakeSellingPrice], [IntakeSellingAmount], [Item No_], [Variant Code], [Unit of Measure Code], [Posting Date], [PurchaseQty], [ReceiptNo], [InventoryBalance], [NewBalance]) VALUES (CAST(10.00000000000000000000 AS Decimal(38, 20)), CAST(1000.000000 AS Decimal(38, 6)), N'1000001', N'NO_SIZE', N'EACH', CAST(0x0000A80800000000 AS DateTime), CAST(100.00000000000000000000 AS Decimal(38, 20)), 1, CAST(0.00000000000000000000 AS Decimal(38, 20)), CAST(100.00000000000000000000 AS Decimal(38, 20)))
GO
INSERT [dbo].[AKTest] ([IntakeSellingPrice], [IntakeSellingAmount], [Item No_], [Variant Code], [Unit of Measure Code], [Posting Date], [PurchaseQty], [ReceiptNo], [InventoryBalance], [NewBalance]) VALUES (CAST(5.00000000000000000000 AS Decimal(38, 20)), CAST(250.000000 AS Decimal(38, 6)), N'1000001', N'NO_SIZE', N'EACH', CAST(0x0000A80E00000000 AS DateTime), CAST(50.00000000000000000000 AS Decimal(38, 20)), 2, CAST(50.00000000000000000000 AS Decimal(38, 20)), CAST(100.00000000000000000000 AS Decimal(38, 20)))
GO
INSERT [dbo].[AKTest] ([IntakeSellingPrice], [IntakeSellingAmount], [Item No_], [Variant Code], [Unit of Measure Code], [Posting Date], [PurchaseQty], [ReceiptNo], [InventoryBalance], [NewBalance]) VALUES (CAST(12.50000000000000000000 AS Decimal(38, 20)), CAST(625.000000 AS Decimal(38, 6)), N'1000001', N'NO_SIZE', N'EACH', CAST(0x0000A81900000000 AS DateTime), CAST(50.00000000000000000000 AS Decimal(38, 20)), 3, CAST(60.00000000000000000000 AS Decimal(38, 20)), CAST(110.00000000000000000000 AS Decimal(38, 20)))
GO
Expected Outcome
ReceiptNo Average
_________________________
1 10.00
2 7.50
3 8.86
The Formular I used to calculate it manually is defined below for the third row. The calculation is better if you start at the bottom first.
A) I start at the bottom using receiptNo 3 where the NewBalance is 110.
B) 50 units are purchased for 12.50 = 625
C) that leaves 60 units. on the previous row 50 units are purchased for 5 = 250
D) that leaves 10 units. on the previous row 100 units are purchased for 10 = 1000. But we only need the cost of 10 so 1000/10 = 100.
E) add all the cost up 625 + 250 + 100 = 975 / 110 = 8.86

Answer 1

I don't think this is possible using ROWS BETWEEN and OVER as the logic is a bit odd?
I created a temporary table to play with the data and test the results, but basically this is just your original script with a recursive CTE added:
CREATE TABLE #AKTest (
[IntakeSellingPrice] [decimal](38, 20) NULL,
[IntakeSellingAmount] [decimal](38, 6) NULL,
[Item No_] [nvarchar](20) NOT NULL,
[Variant Code] [nvarchar](10) NOT NULL,
[Unit of Measure Code] [nvarchar](10) NOT NULL,
[Posting Date] [datetime] NOT NULL,
[PurchaseQty] [decimal](38, 20) NULL,
[ReceiptNo] [bigint] NULL,
[InventoryBalance] [decimal](38, 20) NOT NULL,
[NewBalance] [decimal](38, 20) NULL);
GO
INSERT #AKTest ([IntakeSellingPrice], [IntakeSellingAmount], [Item No_], [Variant Code], [Unit of Measure Code], [Posting Date], [PurchaseQty], [ReceiptNo], [InventoryBalance], [NewBalance]) VALUES (CAST(10.00000000000000000000 AS Decimal(38, 20)), CAST(1000.000000 AS Decimal(38, 6)), N'1000001', N'NO_SIZE', N'EACH', CAST(0x0000A80800000000 AS DateTime), CAST(100.00000000000000000000 AS Decimal(38, 20)), 1, CAST(0.00000000000000000000 AS Decimal(38, 20)), CAST(100.00000000000000000000 AS Decimal(38, 20)))
GO
INSERT #AKTest ([IntakeSellingPrice], [IntakeSellingAmount], [Item No_], [Variant Code], [Unit of Measure Code], [Posting Date], [PurchaseQty], [ReceiptNo], [InventoryBalance], [NewBalance]) VALUES (CAST(5.00000000000000000000 AS Decimal(38, 20)), CAST(250.000000 AS Decimal(38, 6)), N'1000001', N'NO_SIZE', N'EACH', CAST(0x0000A80E00000000 AS DateTime), CAST(50.00000000000000000000 AS Decimal(38, 20)), 2, CAST(50.00000000000000000000 AS Decimal(38, 20)), CAST(100.00000000000000000000 AS Decimal(38, 20)))
GO
INSERT #AKTest ([IntakeSellingPrice], [IntakeSellingAmount], [Item No_], [Variant Code], [Unit of Measure Code], [Posting Date], [PurchaseQty], [ReceiptNo], [InventoryBalance], [NewBalance]) VALUES (CAST(12.50000000000000000000 AS Decimal(38, 20)), CAST(625.000000 AS Decimal(38, 6)), N'1000001', N'NO_SIZE', N'EACH', CAST(0x0000A81900000000 AS DateTime), CAST(50.00000000000000000000 AS Decimal(38, 20)), 3, CAST(60.00000000000000000000 AS Decimal(38, 20)), CAST(110.00000000000000000000 AS Decimal(38, 20)))
GO
SELECT * FROM #AKTest;
WITH cte AS (
SELECT
ReceiptNo,
ReceiptNo AS linked_to,
NewBalance,
NewBalance - PurchaseQty AS remaining,
PurchaseQty AS purchased,
IntakeSellingPrice
FROM
#AKTest
UNION ALL
SELECT
c.ReceiptNo,
c.linked_to - 1 AS linked_to,
a.NewBalance,
c.remaining - a.PurchaseQty AS remaining,
CASE WHEN a.PurchaseQty > c.remaining THEN c.remaining ELSE a.PurchaseQty END AS purchased,
a.IntakeSellingPrice
FROM
cte c
INNER JOIN #AKTest a ON a.ReceiptNo = c.linked_to - 1
WHERE
c.linked_to > 1)
SELECT
ReceiptNo,
SUM(purchased * IntakeSellingPrice) / MAX(NewBalance) AS avg_price
FROM
cte
GROUP BY
ReceiptNo
ORDER BY
ReceiptNo;
Gets the correct answer:
ReceiptNo avg_price
1 10.000000
2 7.500000
3 8.863636
As requested, this will display all of the data from the table, with the average price on the end:
WITH cte AS (
SELECT
ReceiptNo,
ReceiptNo AS linked_to,
NewBalance,
NewBalance - PurchaseQty AS remaining,
PurchaseQty AS purchased,
IntakeSellingPrice
FROM
#AKTest
UNION ALL
SELECT
c.ReceiptNo,
c.linked_to - 1 AS linked_to,
a.NewBalance,
c.remaining - a.PurchaseQty AS remaining,
CASE WHEN a.PurchaseQty > c.remaining THEN c.remaining ELSE a.PurchaseQty END AS purchased,
a.IntakeSellingPrice
FROM
cte c
INNER JOIN #AKTest a ON a.ReceiptNo = c.linked_to - 1
WHERE
c.linked_to > 1),
Averages AS (
SELECT
ReceiptNo,
SUM(purchased * IntakeSellingPrice) / MAX(NewBalance) AS avg_price
FROM
cte
GROUP BY
ReceiptNo)
SELECT
a.*,
v.avg_price
FROM
Averages v
INNER JOIN #AKTest a ON a.ReceiptNo = v.ReceiptNo
ORDER BY
a.ReceiptNo;