get the next id if last one deleted - php

Question

i have bill and product_bill tables.
i need to use bill_id in product_bill table and i should create bill first ,
so id did this
public function store(Request $request)
{
if( Bill::first() == null )
{
$bill_id = 1;
}
else {
$bill_id = Bill::orderBy('id','desc')->first()->id +1 ;
}
// dd($bill_id);
$brand_id = auth('brand')->id();
$bill = new Bill();
$bill->brand_id = $brand_id;
$bill->date = Carbon::today();
$data = $request->all();
$products = [];
$total = 0;
for($i = 0 ; $i<count($data['id']) ; $i++)
{
$prod = new ProductsBill();
$prod->product_id = $data['id'][$i] ;
$prod->quantity = $data['quantity'][$i];
$prod->bill_id = $bill_id;
$products[] = $prod->attributesToArray();
$price = Product::find($prod->product_id)->price;
$total += $price * $prod->quantity;
}
$bill->total = $total;
$bill->save();
ProductsBill::insert($products);
return redirect()->back();
}
when i delete any bill the new bill_id in product_bill table get the next number for last one,
i need to know the id will be create next
thanks.

Answer 1

If you use save() function on your $bill variable, you will get the id by accessing $bill->id. If you want to ensure that you transaction is completed, you could use DB transactions.
use DB;
class ... {
...
public function store(Request $request)
{
$brand_id = auth('brand')->id();
$bill = new Bill();
$bill->brand_id = $brand_id;
$bill->date = Carbon::today();
DB::beginTransaction();
try{
$bill->save();
$data = $request->all();
$products = [];
$total = 0;
for($i = 0 ; $i<count($data['id']) ; $i++)
{
$prod = new ProductsBill();
$prod->product_id = $data['id'][$i] ;
$prod->quantity = $data['quantity'][$i];
$prod->bill_id = $bill->id;
$products[] = $prod->attributesToArray();
$price = Product::find($prod->product_id)->price;
$total += $price * $prod->quantity;
}
$bill->total = $total;
$bill->save();
ProductsBill::insert($products);
DB::commit();
return redirect()->back();
} catch(\Illuminate\Database\QueryException $ex){
DB::rollBack();
// Exception redirect here
}
}
...
}

Answer 2

If I understand your issue correctly, you could probably use the mysql functions to get the last inserted ID and add one to that.
https://dev.mysql.com/doc/refman/8.0/en/information-functions.html#function_last-insert-id