SQL Running Total Reset on Condition - sql

Question

I have the following table:
Transaction History Table
TransactionHistoryId ProductCode Type Quantity PurchasePrice CurrentPrice
1 Product1 B 10 3.00 2.00
2 Product1 B 5 7.00 2.00
3 Product1 S -7 7.00 2.00
4 Product1 S -8 3.00 3.00
5 Product1 B 4 10.00 10.00
6 Product1 B 5 12.00 12.00
8 Product2 B 8 20.00 20.00
I would like to acheive the following table:
TransactionHistoryId ProductCode Type Quantity PurchasePrice QtyRunning PriceRunning
1 Product1 B 10 3.00 10 30.00
2 Product1 B 5 7.00 15 65.00
3 Product1 S -7 7.00 8 65.00
4 Product1 S -8 3.00 0 0.00
5 Product1 B 4 10.00 4 40.00
6 Product1 B 5 12.00 9 100.00
8 Product2 B 8 20.00 8 160.00
Create Table SQL
IF OBJECT_ID('TEMPDB..#TransactionHistory') IS NOT NULL
DROP TABLE #TransactionHistory
create table #TransactionHistory
(TransactionHistoryId int,
ProductCode varchar(10),
Type char(1),
Quantity smallint,
PurchasePrice decimal(18,2),
CurrentPrice decimal(18,2)
)
insert into #TransactionHistory
values
(1,'Product1','B',10,3.00,2.00),
(2,'Product1','B',5,7.00,2.00),
(3,'Product1','S',-7,7.00,2.00),
(4,'Product1','S',-8,3.00,3.00),
(5,'Product1','B',4,10.00,10.00),
(6,'Product1','B',5,12.00,12.00),
(8,'Product2','B',8,20.00,20.00)
Rules
PriceRunningTotal resets when the quantity running total is 0
PriceRunningTotal sums up only Type = 'B' (buys), when Type = 'S' (sold) keep the previous purchase price running total
Notice there is a Product 2 so it should have it's own running count independent of Product 1
Purpose
A query to ultimately find out the following:
Product Quantity AdjustedPurchasePrice
Product1 9 $11.11
Product2 8 $20
I used the following SQL Server 2012 query to get the result, but I feel it could be done much better:
Query
SELECT *,
PriceRunningTotalFinal =
SUM(CASE
WHEN QuantityRunningTotal = 0 THEN -1 * PriceRunningTotal
WHEN Quantity < 0 THEN 0 ELSE PurchasePrice * Quantity END) OVER
(
PARTITION BY ProductCode
ORDER BY TransactionHistoryId ROWS UNBOUNDED PRECEDING
)
FROM (
SELECT TransactionHistoryId, ProductCode, Type, Quantity, PurchasePrice,
QuantityRunningTotal = SUM(Quantity) OVER
(
PARTITION BY ProductCode
ORDER BY TransactionHistoryId ROWS UNBOUNDED PRECEDING
),
PriceRunningTotal = SUM(CASE WHEN Quantity < 0 THEN 0 ELSE PurchasePrice * Quantity END) OVER
(
PARTITION BY ProductCode
ORDER BY TransactionHistoryId ROWS UNBOUNDED PRECEDING
)
FROM TransactionHistory
) AS Results1
ORDER BY ProductCode;
Problem
Ideally I would of liked to use the QuantityRunningTotal within another query but I can't nest windowed functions.
Anyone know of a more efficient way to achieve this result?

Answer 1

Hmmm. I think something like this:
select th.*,
sum(case when type = 'B' then Quantity * PurchasePrice
else 0
end) over (partition by grp, ProductCode order by TransactionHistoryId
) as PriceRunningTotal
from (select th.*,
sum(case when running_quantity = 0 then 1 else 0 end) over (partition by ProductCode order by TransactionHistoryId) as grp
from (select th.*,
sum(quantity) over (partition by ProductCode order by TransactionHistoryId
) as running_quantity
from TransactionHistory th
) th;
I'm not sure if this is the same logic as your query. For this query:
The innermost subquery calculates the running quantity.
The middle subquery calculates a group based on the number of times the running quantity has been 0.
The outermost query then calculates the running price.