通过查询从 MongoDB 中读取数据

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using MongoDB.Bson;
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using MongoDB.Driver;
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// Replace the uri string with your MongoDB deployment's connection string.
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var uri = "mongodb+srv://<user>:<password>@<cluster-url>?retryWrites=true&writeConcern=majority";
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var client = new MongoClient(uri);
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// database and collection code goes here
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var db = client.GetDatabase("sample_guides");
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var coll = db.GetCollection<BsonDocument>("planets");
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// find code goes here
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var cursor = from planet in coll.AsQueryable()
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             where planet["hasRings"] == true
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             select planet;
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// iterate code goes here
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foreach (var document in cursor)
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{
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    Console.WriteLine(document);
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}
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package main
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import (
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	"context"
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	"fmt"
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	"go.mongodb.org/mongo-driver/bson"
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	"go.mongodb.org/mongo-driver/mongo"
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	"go.mongodb.org/mongo-driver/mongo/options"
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)
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func main() {
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	uri := "mongodb+srv://<user>:<password>@<cluster-url>?retryWrites=true&writeConcern=majority"
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	client, err := mongo.Connect(context.TODO(), options.Client().ApplyURI(uri))
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	if err != nil {
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		panic(err)
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	}
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	defer func() {
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		if err = client.Disconnect(context.TODO()); err != nil {
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			panic(err)
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		}
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	}()
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	// database and colletion code goes here
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	db := client.Database("sample_guides")
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	coll := db.Collection("planets")
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	// find code goes here
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	filter := bson.D{{"hasRings", true}}
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	cursor, err := coll.Find(context.TODO(), filter)
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	if err != nil {
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		panic(err)
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	}
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	// iterate code goes here
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	for cursor.Next(context.TODO()) {
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		var result bson.M
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		if err := cursor.Decode(&result); err != nil {
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			panic(err)
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		}
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		fmt.Println(result)
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	}
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	if err := cursor.Err(); err != nil {
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		panic(err)
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	}
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}

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import com.mongodb.client.*;
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import com.mongodb.client.model.Filters.*;
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import org.bson.Document;
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import org.bson.conversions.Bson;
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public class CrudRead {
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    public static void main(String[] args) {
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        String uri = "mongodb+srv://<user>:<password>@<cluster-url>?retryWrites=true&writeConcern=majority";
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        try (MongoClient mongoClient = MongoClients.create(uri)) {
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            // database and collection code goes here
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            MongoDatabase db = mongoClient.getDatabase("sample_guides");
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            MongoCollection<Document> coll = db.getCollection("planets");
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            // find code goes here
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            Bson filter = eq("hasRings", true);
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            MongoCursor<Document> cursor = coll.find(filter).iterator();
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            // iterate code goes here
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            try {
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                while (cursor.hasNext()) {
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                    System.out.println(cursor.next().toJson());
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                }
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            } finally {
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                cursor.close();
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            }
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        }
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    }
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}

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const { MongoClient } = require("mongodb");
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// Replace the uri string with your MongoDB deployment's connection string.
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const uri =
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  "mongodb+srv://<user>:<password>@<cluster-url>?retryWrites=true&writeConcern=majority";
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const client = new MongoClient(uri);
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async function run() {
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  try {
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    await client.connect();
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    // database and collection code goes here
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    const db = client.db("sample_guides");
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    const coll = db.collection("planets");
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    // find code goes here
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    const cursor = coll.find({ hasRings: true });
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    // iterate code goes here
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    await cursor.forEach(console.log);
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  } finally {
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    // Ensures that the client will close when you finish/error
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    await client.close();
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  }
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}
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run().catch(console.dir);

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from pymongo import MongoClient
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# Replace the uri string with your MongoDB deployment's connection string.
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uri = "mongodb+srv://<user>:<password>@<cluster-url>?retryWrites=true&writeConcern=majority"
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client = MongoClient(uri)
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# database and collection code goes here
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db = client.sample_guides
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coll = db.planets
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# find code goes here
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cursor = coll.find({"hasRings": True})
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# iterate code goes here
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for doc in cursor:
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    print(doc)
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# Close the connection to MongoDB when you're done.
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client.close()

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// find code goes here
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var cursor = from planet in coll.AsQueryable()
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             where planet["hasRings"] == false
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             where planet["mainAtmosphere"] == "Ar"
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             select planet;

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// find code goes here
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filter := bson.D{
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	{"$and",
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		bson.A{
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			bson.D{{"hasRings", false}},
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			bson.D{{"mainAtmosphere", "Ar"}},
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		},
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	},
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}
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cursor, err := coll.Find(context.TODO(), filter)
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if err != nil {
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	panic(err)
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}

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// find code goes here
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Bson filter = and(eq("hasRings", false), eq("mainAtmosphere", "Ar"));
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MongoCursor<Document> cursor = coll.find(filter).iterator();

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// find code goes here
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const cursor = coll.find({ hasRings: false, mainAtmosphere: "Ar" });

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# find code goes here
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cursor = coll.find({"hasRings": False, "mainAtmosphere": "Ar"})