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。
$sum
Amazon DocumentDB 中的$sum運算子會傳回群組中每個文件的指定表達式總和。這是一個群組累積器運算子，通常用於彙總管道的 $group 階段，以執行總和計算。
參數
範例 (MongoDB Shell)
下列範例示範如何使用 $sum運算子來計算每個產品的總銷售額。
建立範例文件
db.sales.insertMany([
{ product: "abc", price: 10, quantity: 2 },
{ product: "abc", price: 10, quantity: 3 },
{ product: "xyz", price: 20, quantity: 1 },
{ product: "xyz", price: 20, quantity: 5 }
]);
查詢範例
db.sales.aggregate([
{ $group: {
_id: "$product",
totalSales: { $sum: { $multiply: [ "$price", "$quantity" ] } }
}}
]);
輸出
[
{ "_id": "abc", "totalSales": 50 },
{ "_id": "xyz", "totalSales": 120 }
]
程式碼範例
若要檢視使用 $sum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 uri = 'mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false';
const client = new MongoClient(uri);
try {
await client.connect();
const db = client.db('test');
const collection = db.collection('sales');
const result = await collection.aggregate([
{ $group: {
_id: "$product",
totalSales: { $sum: { $multiply: [ "$price", "$quantity" ] } }
}}
]).toArray();
console.log(result);
} catch (error) {
console.error('Error:', error);
} finally {
await client.close();
}
}
example();
- Python
-
from pymongo import MongoClient
from pprint import pprint
def example():
client = None
try:
client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
db = client.test
collection = db.sales
result = list(collection.aggregate([
{ '$group': {
'_id': '$product',
'totalSales': { '$sum': { '$multiply': [ '$price', '$quantity' ] } }
}}
]))
pprint(result)
except Exception as e:
print(f"An error occurred: {e}")
finally:
if client:
client.close()
example()
