MongoDB Hello World 例子（译）

浏览数：26 / 时间：2015年06月12日

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

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MongoDB Hello World Example

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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。

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Uses?mongod?to start MongoDB.

译：使用 mongod 命令启用MongoDB。

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$./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

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2. Connect MongoDB

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

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

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

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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）。

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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。

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$ ./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" }

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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。

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

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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。

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> 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" }

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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。

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

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> 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。?

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> 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。

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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。

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

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7. Delete Record

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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。

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

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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。

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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。

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> db.users.getIndexes()
[
	{
		"v" : 1,
		"key" : {
			"_id" : 1
		},
		"ns" : "mkyong.users",
		"name" : "_id_"
	}
]
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8.2?To create an index, uses?db.tablename.ensureIndex(column). In below example, an index is created on column “username”.?

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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。

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> 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.?

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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。

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

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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。

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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.?

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References

  1. Official MongoDB tutorials
  2. MongoDB Indexes

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标签： mongodb hello world mongodb hello world

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