Update multiple columns of the table - laravel-5

Question

when I update some columns of the table it insert new field in table
"id": 1,
"invoice_id": "0001-2019-20",
"client_id": "1",
"currency_id": "4",
"date": "2019-06-06",
"subject": "wordpress",
"total": "3000"
when i update only subject and total it will insert new field
"id": 2,
"invoice_id": "",
"client_id": "0",
"currency_id": "0",
"date": "0000-00-00",
"subject": "OMS",
"total": "0"
here is my controller,
$invoices = new Invoice;
$invoices->client_id = $request->get('client_id');
$invoices->currency_id = $request->get('currency_id');;
$invoices->subject = $request->get('subject');
$invoices->save();

Answer 1

The code you are using is for creating a new record.
However you are almost there.
So let's say you want to update below data
{"id": 1,
"invoice_id": "0001-2019-20",
"client_id": "1",
"currency_id": "4",
"date": "2019-06-06",
"subject": "wordpress",
"total": "3000"}
Use Below Code to update that row.
$invoices = Invoice::find($request->get('id'));
$invoices->client_id = $request->get('client_id');
$invoices->currency_id = $request->get('currency_id');
$invoices->subject = $request->get('subject');
$invoices->save();
There are alternative method as below.
$invoices = Invoice::find($request->get('id'));
$invoices->update([
'client_id' => $request->get('client_id'),
'currency_id' => $request->get('currency_id'),
'subject' => $request->get('subject')
]);
Note: For above method array key names and your table column names
must be same.