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。
$ne
$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)
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", "$expectedStatus"] }
}
}
]);
輸出
[
{ _id: 1, orderId: 'A123', status: 'shipped', expectedStatus: 'shipped', needsAttention: false },
{ _id: 2, orderId: 'B456', status: 'pending', expectedStatus: 'shipped', needsAttention: true },
{ _id: 3, orderId: 'C789', status: 'delivered', expectedStatus: 'delivered', needsAttention: false }
]
程式碼範例
若要檢視使用$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()
