Multiple Database on Same Server Join Query

Hi, I had been searching for the solution in the internet for a long time but still I couldn't find the solution, most of the search results is joining on different tables in single database.

I need the solution for different DB::Connection left join and get the query results.

Please noted that I only want to view the results only, no any CRUD required.

Moreover, all databases are within the same server, if using single connection like DB::connection('sqlsrv') or ('sqlsrv2') can get the result easily only when join is having issues.

Below are my codes so far.

<?php

namespace App\Http\Controllers;

use App\UserInfo;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;

class UserInfoController extends Controller
{
    public function index() 
    {       
        // $UserInfos = DB::connection('sqlsrv2')->select('select * from TMS_CLOCKING');                            
        // $userinfos = DB::connection('sqlsrv')->select('select * from userinfo');

        // $userinfos = DB::table('USERINFO')->where('USERID', '=', '252')->get();      
        // $userinfos = DB::table('CHECKINOUT')
        //          ->leftJoin('USERINFO', 'CHECKINOUT.USERID', '=', 'USERINFO.USERID')
        //          ->where('USERINFO.CardNo', '=', '1411078')
        //          ->get();


        // $db = DB::connection('sqlsrv2');

        $employee_profile = 
                    DB::connection('sqlsrv2')
                    ->table('EMPLOYEE')
                    ->where('ISACTIVE', '=', 'Y')
                    ->where('CARDID', '!=', '')
                    ->where('DEPARTMENT', '!=', '')
                    ->get();

        // $employee_attendance =
        //          DB::table('CHECKINOUT')
        //          ->leftJoin('USERINFO', 'CHECKINOUT.USERID', '=', 'USERINFO.USERID')
        //          ->leftJoin('TMS_EMPLOYEE', 'USERINFO.CardNo', '=', 'TMS_EMPLOYEE.CardID')
        //          ->get();

        // $db = DB::Connection('sqlsrv2')->('EMPLOYEE');
        // $employee_attendance =
        //          DB::table('CHECKINOUT')
        //          ->leftJoin('USERINFO', 'CHECKINOUT.USERID', '=', 'USERINFO.USERID')
        //          ->leftjoin($db, 'USERINFO.CardNo', '=', 'EMPLOYEE.CARDID')
        //          ->get();

        $employee_attendance =
                    DB::Connection('sqlsrv')
                    ->table('CHECKINOUT')
                    ->leftJoin('USERINFO', 'CHECKINOUT.USERID', '=', 'USERINFO.USERID')
                    ->leftjoin(DB::Connection('sqlsrv2'))                       
                        ->table('EMPLOYEE', 'USERINFO.CardNo', '=', 'EMPLOYEE.CardID')
                    ->get();

        $employee_attendance = 
                    DB::table(DB::raw('EMPLOYEE'))

        // $userinfos = $employee_profile;
        $userinfos = $employee_attendance;

        return view('userinfo.index', ['userinfos' => $userinfos]);     
    }
}