Laravel - Get sum from different table and calculate - laravel

Question

I'm new in laravel and I need help with this. So I have 3 different table as shown below. I have to calculate the quantity of item based on the different value in the two tables. First, I have to get the sum of the value table 1 and table 2 and group it by the item. After that minus the result and display in item table in my blade by the quantity column
Item table
|ID | Item | quantity |
+---+---------+-------------+
|1 | item1 | |
|2 | item2 | |
|3 | item3 | |
|4 | item4 | |
Value1 table
|ID | Item | value |
+---+---------+-------------+
|1 | item1 | 4757.34 |
|2 | item1 | 938.00 |
|3 | item1 | 0.00 |
|4 | item2 | 6574.3 |
|5 | item2 | 74.40 |
Value2 table
|ID | Item | value |
+---+---------+-------------+
|1 | item1 | 27.64 |
|2 | item1 | 0.00 |
|3 | item1 | 2.00 |
|4 | item2 | 64.34 |
|5 | item2 | 4.40 |
This is what I have done so far
My Eloquent
public function getValue1()
{
$query = Value1::select(DB::raw("SUM(value) as value1"))
->groupBy('item')
->get();
return $query;
}
public function getValue2()
{
$query = Value2::select(DB::raw("SUM(value) as value2"))
->groupBy('item')
->get();
return $query;
}
My Controller
$value1 = $myEloquentRepo->getValue1();
$value2 = $myEloquentRepo->getValue2();
$quantity = $value1 - $value2;
But it seems like I'm not doing it correctly as I got an error Object of class Illuminate\Database\Eloquent\Collection could not be converted to number. Any guide will be appreciated.

Answer 1

That is much simpler to be done with plain SQL. It will be much faster for the server as there will be 3 times less requests to the database.
$query = "INSERT into ItemTable
SELECT t1.item, (t1.qty - t2.qty) as 'quantity'
from (
select Item, sum(value) 'qty'
from table1
group by Item
) t1
join (
select Item, sum(value) 'qty'
from table2
group by Item
) t2 on t1.Item = t2.Item
";
DB::uprepared($query);
the SELECT query itself will return you the needed result. Then based whether your ItemTable is empty or filled, you insert or update into it.