laravel eloquent first or code example

Example 1: laravel eloquent get first

// return first row by id
$user = App\User::where('id',$id)->first();
// or return directly a field
$userId = App\User::where(...)->pluck('id');

Example 2: eloquent first

$user = User::where('mobile', Input::get('mobile'))->get();

if (!$user->isEmpty()){
    $firstUser = $user->first()
}