$month

Amazon DocumentDB 中的$month運算子會以 1 到 12 之間的數字傳回日期的月份。此運算子適用於從日期欄位擷取月份元件，以及執行以日期為基礎的彙總和分析。

參數

• date_expression：這是包含您要從中擷取月份之日期或時間戳記的表達式或欄位。

範例 (MongoDB Shell)

下列範例示範如何使用 $month運算子從日期欄位中擷取月份，並依月份分組資料。

建立範例文件

db.sales.insert([
  { product: "abc123", price: 10.99, date: new Date("2022-01-15") },
  { product: "def456", price: 15.50, date: new Date("2022-02-28") },
  { product: "ghi789", price: 8.25, date: new Date("2022-03-10") },
  { product: "jkl012", price: 12.75, date: new Date("2022-04-05") },
  { product: "mno345", price: 18.99, date: new Date("2022-05-20") }
]);

查詢範例

db.sales.aggregate([
  { $group: { 
      _id: { month: { $month: "$date" } },
      totalSales: { $sum: "$price" }
    }},
  { $sort: { "_id.month": 1 } }
]);

輸出

[
  { _id: { month: 1 }, totalSales: 10.99 },
  { _id: { month: 2 }, totalSales: 15.5 },
  { _id: { month: 3 }, totalSales: 8.25 },
  { _id: { month: 4 }, totalSales: 12.75 },
  { _id: { month: 5 }, totalSales: 18.99 }
]

程式碼範例

若要檢視使用 $month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 groupSalesByMonth() {
  const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');

  try {
    await client.connect();
    const db = client.db('test');
    const collection = db.collection('sales');

    const pipeline = [
      {
        $group: {
          _id: { month: { $month: "$date" } },
          totalSales: { $sum: "$price" }
        }
      },
      {
        $sort: { "_id.month": 1 }
      }
    ];

    const results = await collection.aggregate(pipeline).toArray();

    console.dir(results, { depth: null });

  } finally {
    await client.close();
  }
}

groupSalesByMonth().catch(console.error);

Python

from pymongo import MongoClient

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

    try:
        db = client.test
        collection = db.sales

        pipeline = [
            {
                "$group": {
                    "_id": { "$month": "$date" }, 
                    "totalSales": { "$sum": "$price" }  
                }
            },
            {
                "$sort": { "_id": 1 } 
            }
        ]

        results = collection.aggregate(pipeline)

        for doc in results:
            print(doc)

    except Exception as e:
        print(f"An error occurred: {e}")

    finally:
        client.close()

group_sales_by_month()