FIFO in MySQL db - mysql

Question

I'm using Mysql (not MSSQL) database and bumped onto a problem I seem to be unable to solve. I would very much appreciate your help finding a solution.
I'd like to create a view using two tables, as described below:
1. product_in
product_code
received_time
received_amount
2. product_out
product_code
delivery_time
delivered_amount
The “view” should provide the following:
product_code
received_time
received_amount
of_which_delivered
My problem is that product_out is to be administered to the first incoming data (FIFO: first in first out), but since the amount delivered is either more or less than the received amount, I do not know how to calculate the “of_which_delivered”.
So far, I managed to put into order the incoming data, and sum up the outgoing (delivered) goods using SUM.
SELECT
sn,
product_code,
received_time,
received_amount,
delivered_amount
FROM
( SELECT
received_time,
received_amount,
#rend2 := If( #rend1 = product_code, #rend2 + 1, 1) as sn,
#rend1 := product_code AS product
FROM
product_in,
( SELECT #rend1 := 0, #rend2 := 0 ) AS tt
ORDER BY
product_code,
received_time ) AS k
LEFT JOIN
( SELECT
product_code AS prdct,
SUM(delivered_amount) AS delivered_amount
FROM
product_out
GROUP BY
product_code ) AS b
ON aru = product_code
I have not succeded in creating the loop that would make it possible to analyze if the output amount is more, or less than the received amount on a given day, and if more, then the difference be added to the received amount of another day.
To be more precise, here is an example:
Product Date Qty
nr.1 Sep 2 500
nr.1 Sep 3 300
nr1. Sep 4 200 on the 4th.
900 pcs were delivered out on the 5th.
In this case we should see the following in the view:
Product Action Date Qty
nr.1 received Sep 2 500 (delivered all 500)
nr.1 received Sep 3 300 (delivered all 300)
nr.1 received Sep 4 200 (only 100 delivered)
I would be very grateful to anyone who could help me find a solution!

Answer 1

Sorry no query adjustment for you, but... having worked with accounting systems in the past, your database structure appears short on a better handling of the in/out FIFO method (or even LIFO). What the underlying accounting system had was a inventory table for all receipts (abbreviated)
Table: ItemTrans
ItemTransID (auto-increment ID for any transaction)
ItemID (item id of the inventory item)
Status (status, such as In, Our or Inventory Adjustment)
Date (date of the activity)
Qty (quantity)
QtyUsed (running total column as inventory was used up)
As items were sold or adjustments. the Sales Details table would show which ItemTrans record the quantities were used for. So, if you had inventory on hand as you have in your sample, the sales order detail line would show the 900. The inventory used table would show which specific ItemTransID the quantities were allocated from and how many from said block, thus showing what your intended activity of release of actual product was at the time of sale.
This way, you don't have to recreate what inventory was what at a given point in time. Just query the sales order details and which items they were pulled from to get the data and how many from each block of receipt it went against.
This simplifies the process of generating the COGS (cost of goods sold) as would be reported to the General Ledger from a Sub-journal such as Accounts Receivable (Sales Orders) activity.
Do you have the ability to introduce such adjustments to your database structures?