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# \$1lt
<a name="lt"></a>

Amazon DocumentDB 中的`$lt`運算子用於比對小於指定值的值。此運算子適用於根據數值比較篩選和查詢資料。

**參數**
+ `field`：要檢查的欄位名稱。
+ `value`：要比較的值。

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

下列範例示範如何使用 `$lt`運算子擷取`Inventory.OnHand`值小於 50 的文件。

**建立範例文件**

```
db.example.insertMany([
  { "_id": 1, "Inventory": { "OnHand": 25, "Sold": 60 }, "Colors": ["Red", "Blue"] },
  { "_id": 2, "Inventory": { "OnHand": 75, "Sold": 40 }, "Colors": ["Red", "White"] },
  { "_id": 3, "Inventory": { "OnHand": 10, "Sold": 85 }, "Colors": ["Red", "Green"] }
]);
```

**查詢範例**

```
db.example.find({ "Inventory.OnHand": { $lt: 50 } })
```

**輸出**

```
{ "_id" : 1, "Inventory" : { "OnHand" : 25, "Sold" : 60 }, "Colors" : [ "Red", "Blue" ] }
{ "_id" : 3, "Inventory" : { "OnHand" : 10, "Sold" : 85 }, "Colors" : [ "Red", "Green" ] }
```

## 程式碼範例
<a name="lt-code"></a>

若要檢視使用 `$lt`命令的程式碼範例，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('example');

  const result = await collection.find({ "Inventory.OnHand": { $lt: 50 } }).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['example']

    result = list(collection.find({ "Inventory.OnHand": { "$lt": 50 } }))
    print(result)

    client.close()

example()
```

------