Digital Ocean Site Deployment - Database Insert/update error

I have completed my development in homestead. When I deployed the changes in digitalocean and when i try to submit the records, I am getting the below error and 'query_string' is added in insert/update statements. My application is tested in local development machine (homestead + vagrant) and works fine.

query_string is added in the insert statement. when i monitor my local environment 'query_string' is not added in the insert statement. After deploying into digital ocean, I am getting this error.

i do not know how the query_string is column is added in the insert statement. My controller class is below (it works very well in local homestead)

<?php namespace App\Http\Controllers;

use App\Http\Requests\CountryRequest;
use App\Country;
use Carbon\Carbon;
use Cartalyst\Sentinel\Laravel\Facades\Activation;
use File;
use Hash;
use Illuminate\Http\Request;
use Lang;
use Mail;
use Redirect;
use Sentinel;
use URL;
use View;
use Datatables;
use Validator;

class CountriesController extends Controller
{
    public function index()
    {
        // Show the page
        return view('admin.countries.index', compact('countries'));
    }
    public function data()
    {
        $countries = Country::get(['id', 'name','created_at']);

        return Datatables::of($countries)
            ->edit_column('created_at',function(Country $country) {
                return $country->created_at->diffForHumans();
            })
            ->add_column('actions',function($country) {
                $actions = '<a href='. route('admin.countries.edit', $country->id) .'><i class="livicon" data-name="edit" data-size="18" data-loop="true" data-c="#428BCA" data-hc="#428BCA" title="update country"></i></a>';
                if($user = Sentinel::getUser())
                {
                    if($user->inRole('admin'))
                    {
                        $actions .= '<a href='. route('admin.countries.confirm-delete', $country->id) .' data-toggle="modal" data-target="#delete_confirm"><i class="livicon" data-name="folder-remove" data-size="18" data-loop="true" data-c="#f56954" data-hc="#f56954" title="delete country"></i></a>';
                    }
                }
                return $actions;
            }

            )
            ->make(true);
    }

    /**
     * Create new country
     *
     * @return View
     */
    public function create()
    {
        // Show the page
        return view('admin.countries.create');
    }

    /**
     * Country create form processing.
     *
     * @return Redirect
     */
    public function store(CountryRequest $request)
    {
        $country = new Country($request->all());

        if ($country->save()) {
            return redirect('admin/countries')->with('success', trans('countries/message.success.create'));
        } else {
            return Redirect::route('admin/countries')->withInput()->with('error', trans('countries/message.error.create'));
        }
    }

    /**
     * User update.
     *
     * @param  int $id
     * @return View
     */
    public function edit(Country $country)
    {
        return view('admin.countries.edit', compact('country'));
    }

    /**
     * User update form processing page.
     *
     * @param  Country $country
     * @param UserRequest $request
     * @return Redirect
     */
    public function update(Country $country, CountryRequest $request)
    {
        if ($country->update($request->all())) {
            return redirect('admin/countries')->with('success', trans('countries/message.success.update'));
        } else {
            return Redirect::route('admin/countries')->withInput()->with('error', trans('countries/message.error.update'));
        }
    }

    /**
     * Show a list of all the deleted users.
     *
     * @return View
     */
    public function getDeletedCountries()
    {
        // Grab deleted users
        $countries = Country::onlyTrashed()->get();

        // Show the page
        return view('admin.deleted_countries', compact('countries'));
    }


    /**
     * Delete Confirm
     *
     * @param   Country $country
     * @return  View
     */
    public function getModalDelete(Country $country)
    {
        $model = 'countries';
        $confirm_route = $error = null;
        try {
            $confirm_route = route('admin.countries.delete', ['id' => $country->id]);
            return view('admin.layouts.modal_confirmation', compact('error', 'model', 'confirm_route'));
        } catch (GroupNotFoundException $e) {

            $error = trans('countries/message.error.delete', compact('id'));
            return view('admin.layouts.modal_confirmation', compact('error', 'model', 'confirm_route'));
        }
    }

    /**
     * Delete the given Country.
     *
     * @param  Country $country
     * @return Redirect
     */
    public function destroy(Country $country)
    {
        if ($country->delete()) {
            return redirect('admin/countries')->with('success', trans('countries/message.success.delete'));
        } else {
            return Redirect::route('admin/countries')->withInput()->with('error', trans('countries/message.error.delete'));
        }
    }
}

Please help

QueryException in Connection.php line 770: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'query_string' in 'field list' (SQL: insert into countries (name, query_string, updated_at, created_at) values (USA, , 2017-01-09 10:46:59, 2017-01-09 10:46:59))