Laravel DB select语句。查询返回列名作为结果，而不是值

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateUsersTable extends Migration
{
    public function up()
    {
        Schema::create('users', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->string('email');
            $table->timestamps();
        });
    }

    public function down()
    {
        Schema::dropIfExists('users');
    }
}

$columns = DB::select(DB::raw('SHOW COLUMNS FROM users'));
$columnNames = array_column($columns, 'Field');

return $columnNames;