MongoDB安装及增删改查操作

使用mongodb进行增删改查等基本操作。本例使用 mongodb-win32-i386-2.0.8 , 在windows xp下进行测试。 MongoDB客户端和服务端都运行在本地（同一台机器）。

1.安装MongoDB

1.1.下载mongodb，并解压，本例安装在D:\J2ee\mongodb-win32-i386-2.0.8

1.2.使用mongod.exe启动mongodb

$MongoDB-folder/bin/mongod

D:\J2ee\mongodb-win32-i386-2.0.8\bin>mongod

mongod --help for help and startup options

Mon Dec 24 14:56:35

Mon Dec 24 14:56:35 warning: 32-bit servers don't have journaling enabled by def

ault. Please use --journal if you want durability.

Mon Dec 24 14:56:35

Mon Dec 24 14:56:35 [initandlisten] MongoDB starting : pid=1452 port=27017 dbpat

h=/data/db 32-bit host=chenzhengwei

Mon Dec 24 14:56:35 [initandlisten]

Mon Dec 24 14:56:35 [initandlisten] ** NOTE: when using MongoDB 32 bit, you are

limited to about 2 gigabytes of data

Mon Dec 24 14:56:35 [initandlisten] **       see http://blog.mongodb.org/post/13

7788967/32-bit-limitations

Mon Dec 24 14:56:35 [initandlisten] **       with --journal, the limit is lower

Mon Dec 24 14:56:35 [initandlisten]

Mon Dec 24 14:56:35 [initandlisten] db version v2.0.8, pdfile version 4.5

Mon Dec 24 14:56:35 [initandlisten] git version: a340a57af7cdda865da420704e1d1b2

fac0cedc2

Mon Dec 24 14:56:35 [initandlisten] build info: windows sys.getwindowsversion(ma

jor=6, minor=0, build=6002, platform=2, service_pack='Service Pack 2') BOOST_LIB

_VERSION=1_42

Mon Dec 24 14:56:35 [initandlisten] options: {}

Mon Dec 24 14:56:35 [initandlisten] exception in initAndListen: 10296 dbpath (/d

ata/db) does not exist, terminating

Mon Dec 24 14:56:35 dbexit:

Mon Dec 24 14:56:35 [initandlisten] shutdown: going to close listening sockets..

.

Mon Dec 24 14:56:35 [initandlisten] shutdown: going to flush diaglog...

Mon Dec 24 14:56:35 [initandlisten] shutdown: going to close sockets...

Mon Dec 24 14:56:35 [initandlisten] shutdown: waiting for fs preallocator...

Mon Dec 24 14:56:35 [initandlisten] shutdown: closing all files...

Mon Dec 24 14:56:35 [initandlisten] closeAllFiles() finished

Mon Dec 24 14:56:35 dbexit: really exiting now

以上并没有启动mongod，抛出了以下异常信息：

Mon Dec 24 14:56:35 [initandlisten] exception in initAndListen: 10296 dbpath (/d

ata/db) does not exist, terminating

即dbpath（/data/db)不存在

正确方法,创建目录D:\J2ee\mongodb-win32-i386-2.0.8\data，用于mongodb存放数据。

执行以下命令：

D:\J2ee\mongodb-win32-i386-2.0.8\bin>mongod -dbpath D:\J2ee\mongodb-win32-i386-2

.0.8\data

Mon Dec 24 15:17:03

Mon Dec 24 15:17:03 warning: 32-bit servers don't have journaling enabled by def

ault. Please use --journal if you want durability.

Mon Dec 24 15:17:03

Mon Dec 24 15:17:03 [initandlisten] MongoDB starting : pid=5884 port=27017 dbpat

h=D:\J2ee\mongodb-win32-i386-2.0.8\data 32-bit host=chenzhengwei

Mon Dec 24 15:17:03 [initandlisten]

Mon Dec 24 15:17:03 [initandlisten] ** NOTE: when using MongoDB 32 bit, you are

limited to about 2 gigabytes of data

Mon Dec 24 15:17:03 [initandlisten] **       see http://blog.mongodb.org/post/13

7788967/32-bit-limitations

Mon Dec 24 15:17:03 [initandlisten] **       with --journal, the limit is lower

Mon Dec 24 15:17:03 [initandlisten]

Mon Dec 24 15:17:03 [initandlisten] db version v2.0.8, pdfile version 4.5

Mon Dec 24 15:17:03 [initandlisten] git version: a340a57af7cdda865da420704e1d1b2

fac0cedc2

Mon Dec 24 15:17:03 [initandlisten] build info: windows sys.getwindowsversion(ma

jor=6, minor=0, build=6002, platform=2, service_pack='Service Pack 2') BOOST_LIB

_VERSION=1_42

Mon Dec 24 15:17:03 [initandlisten] options: { dbpath: "D:\J2ee\mongodb-win32-i3

86-2.0.8\data" }

Mon Dec 24 15:17:03 [initandlisten] waiting for connections on port 27017

Mon Dec 24 15:17:03 [websvr] admin web console waiting for connections on port 2

8017

2. 连接MongoDB

再打开一个命令行，执行以下mongo命令:

D:\J2ee\mongodb-win32-i386-2.0.8\bin>mongo
MongoDB shell version: 2.0.8
connecting to: test
>

3. 创建数据库和表

mongodb中使用以下命令，切换到某个数据库（即使它还不存在）

use database-name

mongodb中当你往一个表里面插入一条记录时，相应的表和数据库就被自动创建好了。具体看下面的例子：

D:\J2ee\mongodb-win32-i386-2.0.8\bin>mongo
MongoDB shell version: 2.0.8
connecting to: test
> use mydb
switched to db mydb
> db.users.insert({username:"henry",password:"123456"})
> db.users.find()
{ "_id" : ObjectId("50d803393cc996b4e8ce22de"), "username" : "henry", "password"
: "123456" }
>

以下是三个常用的命令

show dbs – List all databases.
use db_name – Switches to db_name.
show collections – List all tables in the current selected database.

> show dbs
local   (empty)
mydb    0.03125GB
> use mydb
switched to db mydb
> show collections
system.indexes
users
>

Note

In MongoDB, collection means table in SQL.

4. 插入一条记录

插入记录的语法的两种方式：

db.tablename.insert({data}) or db.tablename.save({data})

> db.users.save({username:"google",password:"google123"})
> db.users.find()
{ "_id" : ObjectId("50d803393cc996b4e8ce22de"), "username" : "henry", "password": "123456" }
{ "_id" : ObjectId("50d8046a3cc996b4e8ce22df"), "username" : "google", "password" : "google123" }

5. 更新记录

更新一条记录语法：

db.tablename.update({criteria},{$set: {new value}}).

下面的例子中更新用户henry的密码：

> db.users.update({username:"henry"},{$set:{password:"henry123456"}})
> db.users.find()
{ "_id" : ObjectId("50d8046a3cc996b4e8ce22df"), "username" : "google", "password" : "google123" }
{ "_id" : ObjectId("50d803393cc996b4e8ce22de"), "password" : "henry123456", "username" : "henry" }
>

6. 查询记录

查找记录的语法：

db.tablename.find({criteria}).

6.1 列出users表中的所有记录

> db.users.find()
{ "_id" : ObjectId("50d8046a3cc996b4e8ce22df"), "username" : "google", "password" : "google123" }
{ "_id" : ObjectId("50d803393cc996b4e8ce22de"), "password" : "henry123456", "username" : "henry" }
>

6.2 查询username 为henry的记录

> db.users.find({username:"henry"})
{ "_id" : ObjectId("50d803393cc996b4e8ce22de"), "password" : "henry123456", "username" : "henry" }

7. 删除记录

删除记录的语法：

db.tablename.remove({criteria}).

下面的例子

> db.users.remove({username:"google"})
> db.users.find()
{ "_id" : ObjectId("50d803393cc996b4e8ce22de"), "password" : "henry123456", "username" : "henry" }
>

Note

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

8. 索引

Index（索引）可以提高查询的效率

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

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

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

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

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

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

10. 帮助

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

10.1 help – All available commands.

> 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.

> 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)
db.createCollection(name, { size : ..., capped : ..., max : ... } )
db.currentOp() displays the current operation in the db
db.dropDatabase()
db.eval(func, args) run code server-side
db.getCollection(cname) same as db['cname'] or db.cname
db.getCollectionNames()
db.getLastError() - just returns the err msg string
db.getLastErrorObj() - return full status object
db.getMongo() get the server connection object
db.getMongo().setSlaveOk() allow this connection to read from the nonmas
ter member of a replica pair
db.getName()
db.getPrevError()
db.getProfilingLevel() - deprecated
db.getProfilingStatus() - returns if profiling is on and slow threshold

db.getReplicationInfo()
db.getSiblingDB(name) get the db at the same server as this one
db.isMaster() check replica primary status
db.killOp(opid) kills the current operation in the db
db.listCommands() lists all the db commands
db.logout()
db.printCollectionStats()
db.printReplicationInfo()
db.printSlaveReplicationInfo()
db.printShardingStatus()
db.removeUser(username)
db.repairDatabase()
db.resetError()
db.runCommand(cmdObj) run a database command.  if cmdObj is a string, tu
rns it into { cmdObj : 1 }
db.serverStatus()
db.setProfilingLevel(level,) 0=off 1=slow 2=all
db.shutdownServer()
db.stats()
db.version() current version of the server
db.getMongo().setSlaveOk() allow queries on a replication slave server
db.fsyncLock() flush data to disk and lock server for backups
db.fsyncUnock() unlocks server following a db.fsyncLock()
>

10.3 db.collection.help() – Shows help on collection (table).

> 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.

> 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

Official MongoDB tutorials
MongoDB Indexes