Substracting two Eloquent result tables - php

Question

With Eloquent I get two results like this from my db:
$deliveries = table1::select('place_id','product_id',DB::raw("SUM(amount) as amount"))->groupBy('place_id', 'product_id');
$purchases = table2::select('place_id','product_id',DB::raw("SUM(quantity) as amount"))->groupBy('place_id', 'product_id');
I want to get a table where all the amount entries of table2 are substracted from table1 if
place_id from table1 == place_id from table2
AND
product_id from table1 == product_id from table2
I want to use Eloquent if possible but I am also fine with some raw SQL inside of it or even some fast php-array-method to do something like:
$inventory = $deliveries - $purchases;
edited/added
So right now I do this:
foreach ($deliveries as $delivery => $delivValue) {
foreach ($purchases as $purchase => $purchValue) {
if ($delivValue['place_id']==$purchValue['place_id'] && $delivValue['product_id']==$purchValue['product_id']) {
$deliveries[$delivery]['amount'] = $delivValue['amount'] - $purchValue['amount'];
}
}
}
This works as expected but I think it's very inefficient when the array sizes do increase.

Answer 1

I say this is as close you can get, even if you use laravel's helper method like diff(), etc they still use the same approach internally so your best bet would be to do it at the database level
Try writing this logic at the db level, like
DB::select('
SELECT table1.place_id,table1.product_id,amount,quantity, amount-quantity
FROM table1 JOIN table2
ON (table1.place_id = table2.place_id
and table1.product_id = table2.product_id)
');
http://sqlfiddle.com/#!9/2d5775/6/2
used DB::select - assuming you aren't taking any user input