本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# \$1ne
<a name="ne-aggregation"></a>

`$ne` 彙總運算子會比較兩個值，並在它們不相等`true`時傳回 ，否則傳回 `false`。

**參數**
+ `expression1`：要比較的第一個值。
+ `expression2`：要比較的第二個值。

## 範例 (MongoDB Shell)
<a name="ne-aggregation-examples"></a>

下列範例示範如何使用 `$ne` 運算子來識別具有狀態變更的訂單。

**建立範例文件**

```
db.orders.insertMany([
  { _id: 1, orderId: "A123", status: "shipped", expectedStatus: "shipped" },
  { _id: 2, orderId: "B456", status: "pending", expectedStatus: "shipped" },
  { _id: 3, orderId: "C789", status: "delivered", expectedStatus: "delivered" }
]);
```

**查詢範例**

```
db.orders.aggregate([
  {
    $project: {
      orderId: 1,
      status: 1,
      expectedStatus: 1,
      needsAttention: { $ne: ["$status", "$expectedStatus"] }
    }
  }
]);
```

**輸出**

```
[
  { _id: 1, orderId: 'A123', status: 'shipped', expectedStatus: 'shipped', needsAttention: false },
  { _id: 2, orderId: 'B456', status: 'pending', expectedStatus: 'shipped', needsAttention: true },
  { _id: 3, orderId: 'C789', status: 'delivered', expectedStatus: 'delivered', needsAttention: false }
]
```

## 程式碼範例
<a name="ne-aggregation-code"></a>

若要檢視使用`$ne`彙總運算子的程式碼範例，請選擇您要使用的語言標籤：

------
#### [ Node.js ]

```
const { MongoClient } = require('mongodb');

async function example() {
  const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');
  const db = client.db('test');
  const collection = db.collection('orders');

  const result = await collection.aggregate([
    {
      $project: {
        orderId: 1,
        status: 1,
        expectedStatus: 1,
        needsAttention: { $ne: ["$status", "$expectedStatus"] }
      }
    }
  ]).toArray();

  console.log(result);
  await client.close();
}

example();
```

------
#### [ Python ]

```
from pymongo import MongoClient

def example():
    client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
    db = client['test']
    collection = db['orders']

    result = list(collection.aggregate([
        {
            '$project': {
                'orderId': 1,
                'status': 1,
                'expectedStatus': 1,
                'needsAttention': { '$ne': ['$status', '$expectedStatus'] }
            }
        }
    ]))

    print(result)
    client.close()

example()
```

------