mongodb 基础(一)创建集合,简单查询、移除集合种文档文档 1、create a collection the name is users(the users collection contains field :createDate、name、age、grade) example: db.users.insertMany([{"createDate":"2024-01-10","name":"zhangsan","age":20,"grade":3},{"createDate":"2024-01-10...
ExampleGet your own Python Server Create a collection called "customers": importpymongo myclient = pymongo.MongoClient("mongodb://localhost:27017/") mydb = myclient["mydatabase"] mycol = mydb["customers"] Run example » Important:In MongoDB, a collection is not created until it gets co...
MongoDB removes older documents if a collection reaches the maximum size limit before it reaches the maximum document count. Consider the following example: copy copied db.createCollection("log", { capped : true, size : 5242880, max : 5000 } ) This command creates a collection named log ...
For example, you use db.createCollection() to create a capped collection, or to create a new collection that uses document validation. db.createCollection() is also used to pre-allocate space for an ordinary collection. db.createCollection() is a wrapper around the database command create. ...
下面的示例代码展示了如何连接到 MongoDB、创建 Collection 并插入文档。 importcom.mongodb.MongoClient;importcom.mongodb.MongoClientURI;importcom.mongodb.client.MongoCollection;importcom.mongodb.client.MongoDatabase;importorg.bson.Document;publicclassMongoDBExample{publicstaticvoidmain(String[]args){// 连接...
db.createCollectionExample The followingdb.createCollection()example adds aclustered collectionnamedstocks: db.createCollection( "stocks", {clusteredIndex: {"key": {_id:1},"unique":true,"name":"stocks clustered key"} } ) In the example,clusteredIndexspecifies: ...
使用弱类型collection进行CRUD: var entry = new DemoEntry { Uuid = uuid, Value = "1" }; Console.WriteLine("-- BsonDocument CRUD ---"); var filter = Builders<BsonDocument>.Filter.Eq("Uuid", uuid); // Create Console.WriteLine("[Create] " + entry); await _bsonCollection.ReplaceOneAsync...
db.users.insertOne({name:"Alice",age:30,email:"alice@example.com"}) 1. 2. 3. 4. 5. 2. 插入多个文档 如果要插入多个文档,可以使用insertMany()方法。例如: db.users.insertMany([{name:"Bob",age:25,email:"bob@example.com"},{name:"Carol",age:28,email:"carol@example.com"},{name:"...
连接replica pair, 服务器1为example1.com服务器2为example2。 连接replica set 三台服务器 (端口 27017, 27018, 和27019): 连接replica set 三台服务器, 写入操作应用在主服务器 并且分布查询到从服务器。 直接连接第一个服务器,无论是replica set一部分或者主服务器或者从服务器。
db.mycollection.insert({name:"John Doe",age:30,email:"john@example.com"}) 此命令将向名为“mycollection”的集合中插入一个名为“user”的文档。 MongoDB还支持在插入文档时自动创建集合。例如,要将一个名为“order”的文档插入到名为“mycollection2”的集合中,请在mongo shell中运行以下命令: ...