MongoDB Hello World 例子（译）

 

原文出自：http://www.mkyong.com/mongodb/mongodb-hello-world-example/

返回目录：http://ysj5125094.iteye.com/blog/2192754 

 

MongoDB Hello World Example

 

A quick guide to show you how to do basic operations like create, update, find, delete record and indexing in MongoDB. This example is using MongoDB 2.0.7, running on Mac OS X 10.8, both MongoDB client and server console are run on localhost, same machine.

译：一个快速指南，告诉你如何在MongoDB中做基本的操作如创建，更新，删除记录和索引。这个例子是使用MongoDB 2.0. 7，在MAC OS X 10.8的运行，无论是MongoDB的客户端和服务器控制台上运行的本地主机，同一台机器。

1. Install MongoDB

Install MongoDB on Windows(译), Ubuntu(待译) or Mac OS X(待译). The installation is easy, basically just download the MongoDB zip file, extra and run the command – $MongoDB-folder/bin/mongod.

译：在Windows，Ubuntu或MAC OS X 上安装MongoDB非常容易，基本上只是下载MongoDB ZIP文件，额外的运行命令 – $MongoDB-folder / bin / mongod。

 

Uses mongod to start MongoDB.

译：使用 mongod 命令启用MongoDB。

 

 

$./mongod
Tue Sep 11 21:55:36 [initandlisten] MongoDB starting : 
pid=72280 port=27017 dbpath=/data/db/ 64-bit host=Yongs-MacBook-Air.local
Tue Sep 11 21:55:36 [initandlisten] db version v2.0.7, pdfile version 4.5
Tue Sep 11 21:55:36 [initandlisten] options: {}
Tue Sep 11 21:55:36 [initandlisten] journal dir=/data/db/journal
Tue Sep 11 21:55:36 [initandlisten] recover : no journal files present, no recovery needed
Tue Sep 11 21:55:36 [websvr] admin web console waiting for connections on port 28017
Tue Sep 11 21:55:36 [initandlisten] waiting for connections on port 27017

 

2. Connect MongoDB

To connect MongoDB, uses $MongoDB-folder/bin/mongo

译：使用 $MongoDB-folder / bin / mongo 命令来连接MongoDB。

 

$ ./mongo
MongoDB shell version: 2.0.7
connecting to: test

 

3. Create a database or table (collection)

译：创建一个数据库或表（集合），在MongoDB中表被称做集合。

In MongoDB, both database and table are created automatically when the first time data is inserted. Uses use database-name, to switch to your database (even this is not created yet).

译：在MongoDB中，第一次插入数据时数据库和表自动创建。使用 use database - name 命令，切换到您的数据库（即使这个仍未被创建）。

 

In below example, after you inserted a single record, database “mkyong”, and table “users” are created on the fly.

译：在下面的例子中，当你插入一个记录后，数据库 "mkyong" 和表 "users" 是动态创建的。

 

$ ./mongo
MongoDB shell version: 2.0.7
connecting to: test
> use mkyong
switched to db mkyong
 
> db.users.insert({username:"mkyong",password:"123456"})
> db.users.find()
{ "_id" : ObjectId("504f45cd17f6c778042c3c07"), "username" : "mkyong", "password" : "123456" }

 

 

Three database commands you should know.

译：以下三个关于数据库的命令，你应该知道。

1. show dbs – List all databases.译：显示所有数据库列表
2. use db_name – Switches to db_name.译：打开db_name数据库。
3. show collections – List all tables in the current selected database.译：当前选定的数据库中所有表的集合（列表）。

Note
In MongoDB, collection means table in SQL.

译：在MongoDB中，collection 相当于SQL中的 table。

4. Insert A Record

To insert a record, uses db.tablename.insert({data}) or db.tablename.save({data}), both works, no idea why MongoDB created both.

译：使用 db.tablename.insert({data}) 或 db.tablename.save({data})都可以在MongoDB中插入一条新的记录。

 

> db.users.save({username:"google",password:"google123"})
> db.users.find()
{ "_id" : ObjectId("504f45cd17f6c778042c3c07"), "username" : "mkyong", "password" : "123456" }
{ "_id" : ObjectId("504f48ea17f6c778042c3c0a"), "username" : "google", "password" : "google123" }

 

5. Update A Record

To update a record, uses db.tablename.update({criteria},{$set: {new value}}). In below example, the password of username : “mkyong” is updated.

译：使用 db.tablename.update({criteria},{$set:{new value}})命令更新一条记录。下面的例子中，将用户名为“mkyong”的密码更新。

 

> db.users.update({username:"mkyong"},{$set:{password:"hello123"}})
> db.users.find()
{ "_id" : ObjectId("504f48ea17f6c778042c3c0a"), "username" : "google", "password" : "google123" }
{ "_id" : ObjectId("504f45cd17f6c778042c3c07"), "password" : "hello123", "username" : "mkyong" }

 

6. Find Records

To find or query records, uses db.tablename.find({criteria}).

译：使用 db.tablename.find({criteria}) 命令寻找或查询记录。

 

6.1 List all records from table “users”.译：从表"users"中获取用户列表。

 

> db.users.find()
{ "_id" : ObjectId("504f48ea17f6c778042c3c0a"), "username" : "google", "password" : "google123" }
{ "_id" : ObjectId("504f45cd17f6c778042c3c07"), "password" : "hello123", "username" : "mkyong" }

6.2 Find records where username is “google”.译：查询username是"google"的记录。 

 

 

> db.users.find({username:"google"})
{ "_id" : ObjectId("504f48ea17f6c778042c3c0a"), "username" : "google", "password" : "google123" }

6.3 Find records where username’s length is less than or equal to 2.译： 查询username长度小于或等于2的记录。

 

 

db.users.find({$where:"this.username.length<=2"})

6.4 Find records where username field is existed. 译：查询不存在username字段的记录。

 

 

db.users.find({username:{$exists : true}})

 

7. Delete Record

 

To delete a record, uses db.tablename.remove({criteria}). In below example, the record of username “google” is deleted.

译：使用 db.tablename.remove({criteria}) 命令删除记录。在下面例子中告诉你如何删除username是"google"的记录。

 

> db.users.remove({username:"google"})
> db.users.find()
{ "_id" : ObjectId("504f45cd17f6c778042c3c07"), "password" : "hello123", "username" : "mkyong" }

 

 

Note
To delete all records from a table, uses db.tablename.remove().
To drop the table, uses db.tablename.drop().

译1：使用 db.tablename.remove() 命令删除表中所有记录。

译2：使用 db.tablename.drop() 命令删除表。

8. Indexing

Index may help you increase the speed of querying data.

译：索引可以帮助你提高数据查询速度。

 

8.1 List all indexes of table “users”, by default the column “_id” is always the primary key and created automatically.

译："users"表的所有索引列表，默认情况下 "_id" 字段是自动创建主键的。

 

> db.users.getIndexes()
[
	{
		"v" : 1,
		"key" : {
			"_id" : 1
		},
		"ns" : "mkyong.users",
		"name" : "_id_"
	}
]
>

8.2 To create an index, uses db.tablename.ensureIndex(column). In below example, an index is created on column “username”. 

 

译：使用 db.tablename.ensureIndex(column) 命令创建一个索引。在下面例子中，在"username"字段上创建一个索引。

 

> db.users.ensureIndex({username:1})
> db.users.getIndexes()
[
	{
		"v" : 1,
		"key" : {
			"_id" : 1
		},
		"ns" : "mkyong.users",
		"name" : "_id_"
	},
	{
		"v" : 1,
		"key" : {
			"username" : 1
		},
		"ns" : "mkyong.users",
		"name" : "username_1"
	}
]

8.3 To drop an index, uses db.tablename.dropIndex(column). In below example, the index on column “username” is deleted or dropped. 

 

译：使用 db.tablename.dropIndex(column) 命令删除一个索引。 在下面例子中，删除 "username" 字段上的索引。

 

> db.users.dropIndex({username:1})
{ "nIndexesWas" : 2, "ok" : 1 }
> db.users.getIndexes()
[
	{
		"v" : 1,
		"key" : {
			"_id" : 1
		},
		"ns" : "mkyong.users",
		"name" : "_id_"
	}
]
>

8.4 To create an unique index, uses db.tablename.ensureIndex({column},{unique:true}). In below example, an unique index is created on column “username”. 

 

译：使用 db.tablename.ensureIndex({column},{unique:true}) 命令创建唯一索引。 在下面例子中，为"username"字段创建一个唯一索引。

> db.users.ensureIndex({username:1},{unique:true});
> db.users.getIndexes()
[
	{
		"v" : 1,
		"key" : {
			"_id" : 1
		},
		"ns" : "mkyong.users",
		"name" : "_id_"
	},
	{
		"v" : 1,
		"key" : {
			"username" : 1
		},
		"unique" : true,
		"ns" : "mkyong.users",
		"name" : "username_1"
	}
]

10. Help

At last, uses help() to guide you how to do things in MongoDB.

译：最后，使用 help() 命令来获取帮助信息。

 

10.1 help – All available commands.译：所有可用的命令信息。

> help
	db.help()                    help on db methods
	db.mycoll.help()             help on collection methods
	rs.help()                    help on replica set methods
	help admin                   administrative help
	help connect                 connecting to a db help
	help keys                    key shortcuts  
	//...

10.2 db.help() – Shows help on db.译：显示db级别的帮助信息。 

> db.help()
DB methods:
	db.addUser(username, password[, readOnly=false])
	db.auth(username, password)
	db.cloneDatabase(fromhost)
	db.commandHelp(name) returns the help for the command
	db.copyDatabase(fromdb, todb, fromhost)
	//...

10.3 db.collection.help() – Shows help on collection (table).译：显示集合级别的帮助信息。 

> db.users.help()
DBCollection help
	db.users.find().help() - show DBCursor help
	db.users.count()
	db.users.dataSize()
	db.users.distinct( key ) - eg. db.users.distinct( 'x' )
	db.users.drop() drop the collection
	db.users.dropIndex(name)
	//...

10.4 db.collection.function.help() – Shows help on function.译：显示函数级别的帮助信息。  

> db.users.find().help()
find() modifiers
	.sort( {...} )
	.limit( n )
	.skip( n )
	.count() - total # of objects matching query, ignores skip,limit
	.size() - total # of objects cursor would return, honors skip,limit
	.explain([verbose])
    //...

Done. Hope this summary of MongoDB commands could help others. 

 

References

1. Official MongoDB tutorials
   
2. MongoDB Indexes