CodeIgniter MongoDB extension using aggregate to implement the Sum method

This post consists of: http://xinpure.com/2015/01/07/codeigniter-mongodb%e6%89%a9%e5%b1%95%e4%b9%8b%e4%bd%bf%e7%94%a8aggregate% e6%96%b9%e6%b3%95%e5%ae%9e%e7%8e%b0mysql%e7%9a%84sum%e6%96%b9%e6%b3%95/

CodeIgniter MongoDB extension using aggregate to implement the Sum method

Here's Codeigniter MongoDB an extension that I added when I was using the extension

Is the MongoDB Aggregate method used Mysql in the Sum implementation

/* Controller.php */$option = array (    array (            ‘$match‘ => array (                    ‘match_1‘ => ‘value_1‘,                    ‘match_2‘ => ‘value_2‘            )    ),    array (            ‘$group‘ => array (                    ‘_id‘   => null,                    ‘sum_1‘ => [‘$sum‘ => ‘$amount_1‘],                    ‘sum_2‘ => [‘$sum‘ => ‘$amount_2‘],                    ‘sum_3‘ => [‘$sum‘ => ‘$amount_3‘]            )        ));$result = $this -> mongo_db -> aggregate(‘collection‘,   $option);/* Mongo_db.php */public function aggregate ($collection, $option = array()){    try {            return $this -> db -> {$collection} -> aggregate($option);    }    catch (Exception $e) {            show_error("Unable to aggregate Mongo Databases: {$e->getMessage()}", 500);    }}

CodeIgniter MongoDB extension using aggregate to implement the Sum method