Fifo inventory in codeigniter - php

Question

I'm new to CodeIgniter. I'm trying to update the quantity of the table based on FIFO. I'm making a stock take page, if we count the physical item less than what the table has, we will reconcile and this will update the inventory table and the discard table. Updating inventory table is easy and I've done but I want to update the discard table's quantity based on FIFO. What I want is for example the quantity of item A in inventory table is 50 but when we count it physically it's 35, so when we reconcile, it should minus 15 from the discard table quantity.
Items
Qty
Date
Item A
5
2022-8-22
Item A
4
2022-8-22
Item A
9
2022-8-22
After update it should be like:
| Items | Qty | Date |
|:--------|:------:| --------:|
| Item A | 0 | 2022-8-22|
| Item A | 0 | 2022-8-22|
| Item A | 3 | 2022-8-22|
Please help me. If you need further clarification, do let me know. Thanks in advance
public function update_complete(){
$stock_diff = $this->input->post('stock_diff');
$counted_stock_value = $this->input->post('counted_stock_value');
$cost_diff = $this->input->post('cost_diff');
$reconcile = $this->input->post('reconcile');
$barcode = $this->input->post('barcode');
$stk_id = $this->input->post('stk_id');
for ($i = 0; $i < count($barcode); $i++)
{
$data = array(
'stocktake_value' => $counted_stock_value[$i],
'stock_diff' => $stock_diff[$i],
'cost_diff' => $cost_diff[$i],
'status' => $reconcile[$i]
);
// Commented for testing
$this->db->where('stk_id', $stk_id);
$this->db->where('barcode', $barcode[$i]);
$this->db->update('stocktake_trans', $data);
$itemResult = $this->item_model->getStockdiscardTransByBarcodeNew($barcode[$i]);
foreach($itemResult as $item)
{
$rest = $stock_diff[$i];
if($rest > 0)
{
if($item['quantity'] >= $rest)
{
$rest = $item['quantity']-=$rest;
//$rest = 0;
echo $rest;
}
else
{
$item['quantity'] = 0;
$rest = $rest - $item['quantity'];
}
$this->db->where('barcode', $barcode[$i]);
$this->db->update('stockdiscard_trans', array('quantity' => $rest));
}
}
}
// Update Stock Take
$data1 = array(
'reconciled_by' => $this->session->userdata('name'),
'reconciled_at' => date('Y-m-d')
);
$this->db->where('id', $stk_id);
$this->db->update('stocktake', $data1);
// Set message
$this->session->set_flashdata('stocktake_reconciled', 'Stock Take has been Reconciled!');
//redirect('stocktake/complete');
}

Answer 1

I understand you want to store the difference between the old stock and the new stock.
You can store the original quantity in a variable, update the product with the new value, and then do the difference between the original quantity and the new quantity. Finally, you store the difference in the discard table.
Is what I understood correct?
Edit 1:
Something like this?
$itemsModel = model('App\Models\itemsModel');
$totalDB = $itemsModel->where('Items', 'Item A')->select('sum(Qty)')->first(); // let say 50
$totalMag = 35;
$rest = $totalDB - $totalMag; // rest 50-35 = 15
$itemResult = $itemsModel->where('Items', 'Item A')->findAll();
foreach($itemResult as $item)
{
if($rest > 0)
{
if($item->Qty >= $rest)
{
$item->Qty -= $rest;
$rest = 0;
}
else
{
$item->Qty = 0;
$rest = $rest - $item->Qty;
}
$item->save();
}
}
Backtesting:
-remaining qty 15
5 >= 15? - FALSE
Qty = 0
Rest = 10
4 >= 10 FALSE
Qty = 0
Rest = 6
9 >= 6 TRUE
Qty = 9-6 = 3
Rest = 0
But you need to manage, for what will happen if the remaining stock of products will be more than 0 and the quantity of products A will be 0.
Lets say we have remaining qty to 19
5 >= 19? False
Qty = 0
Rest = 14
4 >= 14? False
Qty = 0
Rest = 10
9 >= 10? False
Qty = 0
Rest = 1
What will happen for the rest = 1 when all item in our table have 0 Qty?