php 将一个二维数组中两个相同的value 相同 指定值相加

array(3) {
  [0]=>
  array(7) {
    ["mlid"]=>
    int(1)
    ["num"]=>
    int(1)
    ["ctime"]=>
    string(19) "2018-04-11 16:56:27"
    ["cyear"]=>
    string(4) "2018"
    ["cmonth"]=>
    string(7) "2018-04"
    ["cweek"]=>
    string(7) "2018-15"
    ["cdate"]=>
    string(10) "2018-04-11"
  }
  [1]=>
  array(7) {
    ["mlid"]=>
    int(1)
    ["num"]=>
    int(1)
    ["ctime"]=>
    string(19) "2018-04-11 16:57:33"
    ["cyear"]=>
    string(4) "2018"
    ["cmonth"]=>
    string(7) "2018-04"
    ["cweek"]=>
    string(7) "2018-15"
    ["cdate"]=>
    string(10) "2018-04-11"
  }
  [2]=>
  &array(7) {
    ["mlid"]=>
    int(2)
    ["num"]=>
    int(1)
    ["ctime"]=>
    string(19) "2018-04-12 08:53:17"
    ["cyear"]=>
    string(4) "2018"
    ["cmonth"]=>
    string(7) "2018-04"
    ["cweek"]=>
    string(7) "2018-15"
    ["cdate"]=>
    string(10) "2018-04-12"
  }
}

　　

$result = array();
            foreach($MemberAccount as $val){
                $key = $val['mlid'].'_'.$val['cdate'];
                if(!isset($result[$key])){
                    $result[$key] = $val;
                }else{
                    $result[$key]['num'] += $val['num'];
                }
            }