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。

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

`$gt` 彙總運算子會比較兩個值，如果第一個值大於第二個值`true`，則傳回 ，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="gt-aggregation-examples"></a>

下列範例示範如何使用 `$gt` 運算子來識別超過價格閾值的產品。

**建立範例文件**

```
db.products.insertMany([
  { _id: 1, name: "Laptop", price: 1200 },
  { _id: 2, name: "Mouse", price: 25 },
  { _id: 3, name: "Monitor", price: 400 }
]);
```

**查詢範例**

```
db.products.aggregate([
  {
    $project: {
      name: 1,
      price: 1,
      expensive: { $gt: ["$price", 100] }
    }
  }
]);
```

**輸出**

```
[
  { _id: 1, name: 'Laptop', price: 1200, expensive: true },
  { _id: 2, name: 'Mouse', price: 25, expensive: false },
  { _id: 3, name: 'Monitor', price: 400, expensive: true }
]
```

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

若要檢視使用`$gt`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('products');

  const result = await collection.aggregate([
    {
      $project: {
        name: 1,
        price: 1,
        expensive: { $gt: ["$price", 100] }
      }
    }
  ]).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['products']

    result = list(collection.aggregate([
        {
            '$project': {
                'name': 1,
                'price': 1,
                'expensive': { '$gt': ['$price', 100] }
            }
        }
    ]))

    print(result)
    client.close()

example()
```

------