MS SQL FIFO Partial transfers - sql

Question

I have a number of transactions that transfer inventory from one account to another account. I can transfer all inventory and I can transfer partial inventory.
I need to pay commission to the owner of the account where inventory resides at my commission date.
My report needs to show the original origin of the inventory items if they have transferred and provide a unit_balance that I can calculate commission from.
Example Transactions:
Account 100
Account, trxid, transacted_units, transactiontype, transferfrom, transferto, date
100, 1, 100, buy, NULL, NULL, 1/1/2020
100, 2, 50, transfer in, 200, NULL, 1/2/2020
Account 200
Account, trxid, transacted_units, transactiontype, transferfrom, transferto, date
200, 3, 40, buy, NULL, NULL, 12/1/2019
200, 4, 30, buy, NULL, NULL, 12/2/2019
200, 5, 7, sell, NULL, NULL, 12/3/2019
200, 6, 50, transfer out, NULL, 100, 1/2/2020
My report output needs to show the full details of accounts associated with the inventory that relates to the unit_balance
Report Output:
[level], Account, trxid, parenttrxid, transacted_units, transactiontype, transferfrom, transferto, date, units_balance
0, 100, 1, NULL, 100, buy, NULL, NULL, 1/1/2020, 100
0, 100, 2, NULL, 50, transfer in, 200, NULL, 1/2/2020, NULL
1, 200, 3, 2, 40, buy, NULL, NULL, 12/1/2019, 33
1, 200, 4, 2, 30, buy, NULL, NULL, 12/2/2019, 17
1, 200, 5, 2, 7, sell, NULL, NULL, 12/3/2019, 0
1, 200, 6, 2, 50, transfer out, NULL, 100, 1/2/2020, 0
*The FIFO logic applies the 7 units sold to the first buy for account 200. The transfer out should then calculate the units_balance on the remaining eligible transactions.
The SQL code I have today only works when I transfer out the full inventory amount, not partial transfers:
select
[level],
parentid,
trxid,
account,
transactiontype,
date,
rnk,
transacted_units,
cumulative,
CASE
WHEN cumulative>0 and transacted_units>=cumulative THEN cumulative
WHEN cumulative>0 and transacted_units<cumulative THEN transacted_units
ELSE 0
END units_bal
from (
select
*,
sum(transacted_units*Positive_Negative_Indicator) over (partition by parenttrxid, account order by rnk, date, trxid RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING ) cumulative
from (
select *,
CASE
WHEN transacted_units*Positive_Negative_Indicator < 0 THEN 0
ELSE ROW_NUMBER() OVER (PARTITION BY parenttrxid, account ORDER BY Positive_Negative_Indicator ASC, date ASC, trxid ASC)
END rnk
from Transactions
) a
) a
The positive_negative_indicator field represents the direction of a transaction. A sell or transfer out is negative whereas the others are positive.

Answer 1

for each current "in" transaction, calculate the running total (of units) for the previous "in" transactions. Then assign as many "out" units that haven't been consumed by the previous "in" transactions (as many "out" units== running total of "out" units, that can be consumed by the current "in" transaction).
declare #t table
(
Account int,
trxid int,
trunits int,
trtype varchar(20),
transfrom int,
transto int,
thedate date
);
insert into #t(Account, trxid, trunits, trtype, transfrom, transto, thedate)
values
(100, 1, 100, 'buy', NULL, NULL, '20200101'),
(100, 2, 50, 'transfer in', 200, NULL, '20200201'),
(200, 3, 40, 'buy', NULL, NULL, '20190112'),
(200, 4, 30, 'buy', NULL, NULL, '20190213'),
(200, 5, 10, 'buy', NULL, NULL, '20190214'),
(200, 6, 7, 'sell', NULL, NULL, '20190315'),
(200, 7, 9, 'sell', NULL, NULL, '20190316'),
(200, 8, 25, 'buy', NULL, NULL, '20190317'),
(200, 9, 39, 'sell', NULL, NULL, '20190318'),
(200, 10, 18, 'sell', NULL, NULL, '20190319'),
(200, 11, 14, 'sell', NULL, NULL, '20190320'),
(200, 11, 50, 'transfer out', NULL, 100, '20200201');
select *, case when t.trtype not in ('sell', 'transfer out') then t.trunits -isnull(otu.out_units, 0) else null end as leftover_units
from
(
select *, sum(case when trtype not in ('sell', 'transfer out') then trunits else 0 end) over (partition by Account order by thedate rows between unbounded preceding and 1 preceding) as previous_in_running_units
from #t
) as t
outer apply
(
select top (1) ort.out_units_running_total - isnull(t.previous_in_running_units, 0) as out_units
from
(
select sum(o.trunits) over(order by o.thedate) as out_units_running_total
from #t as o
where o.trtype in ('sell', 'transfer out')
and o.Account = t.Account
and t.trtype not in ('sell', 'transfer out') --no calculations needed when cross applying for "out" transactions
) as ort --out running totals
where ort.out_units_running_total-isnull(t.previous_in_running_units, 0) <= t.trunits --<-- ("in") use as many out units as can be consumed by current t.transaction/date after deducting what has been consumed by the previous t.transaction/date
and ort.out_units_running_total-isnull(t.previous_in_running_units, 0) > 0 --not needed(?) if balance is guaranteed.. total_out = total_in
order by ort.out_units_running_total desc
) as otu; --"out units"