//先定義
$this->collection = (new \MongoDB\Client($host))->selectDatabase('my_db')->selectCollection('my_collection');

1.使用$inc，實現數值疊加

        $updateUser = [
                '$inc'=>[
                        "total_amount"=> 10
                ]
        ];
        $userFilter = [
            '_id'
 
 => '123',
        ];

       $this->collection->updateOne($userFilter, $updateUser);

• 讓指定collection中“_id”為“123的資料，“total_amount”欄位加上10，若操作前前”total_amount”的值為8，則操作後值為18.

2.將cursor轉換成array

$res = $this->collection->find()->toArray();
$res = json_encode($res);

3.option中引數的順序問題

//skip、limit須在project之前否則報錯
 

$query  = [];
$option = [
'skip'       => 0,
'limit'      => 5,
'sort'      => [
                'create_time' => -1,
],
'projection' => [
                '_id'    => 1,
                'icon'   => 1,
             ]
    ];

$res = $this->collection->find($query,$option)->toArray();
 

4.empty()檢驗MongoDB 物件

$query  = ['name'=>'mike'];
$cursor = $this->collection->findOne($query);
//若不存在name 為mike的資料，則列印$cursor結果為true，反之為false
var_dump(empty($cursor));

5.統計符合條件的資料總數
```php
$query  = ['name'=>'mike'];
$count  = $this->collection->count($query);

“`