php - Laravel 4 how to merge database tables and order them by created_at? -

i have 4 database tables want merge together, , want order data created_at field. code data still grouped per database table, result should sort of timeline of tables data. doing wrong? showing 4 items...

public function showindex() {      $users = user::orderby('created_at', 'desc')->get();     $projects = project::with('votes')->orderby('created_at', 'desc')->get();     $events = calendar::orderby('created_at', 'desc')->get();     $jobs = job::orderby('created_at', 'desc')->get();      $all = $users->merge($projects)->merge($events)->merge($jobs);      return view::make('users.index')->with('events', $all);  } 

assuming problem fact it's not order properly, can use

$all->sort(function ($a, $b) {     if ($a->created_at === $b->created_at) {         return 0;     }       return $a->created_at > $b->created_at ? 1 : -1; }); 

or

$all = $all->sortby(function($result) {     return $result->created_at; }); 

see http://laravel.com/api/master/illuminate/support/collection.html#method_sort