MongoDB学习资料四---MongoDB的使用技巧（四）

如果想查看当前连接在哪个数据库下面，可以直接输入db

CODE:

> db
Admin想切换到test数据库下面

CODE:

> use test
switched to db test
> db
Test想查看test下有哪些表或者叫collection，可以输入

CODE:

> show collections
system.indexes
user想知道mongodb支持哪些命令，可以直接输入help

CODE:

> help
HELP
        show dbs                     show database names
        show collections             show collections in current database
        show users                   show users in current database
        show profile                 show most recent system.profile entries with time >= 1ms
        use <db name>                set curent database to <db name>
        db.help()                    help on DB methods
        db.foo.help()                help on collection methods
        db.foo.find()                list objects in collection foo
        db.foo.find( { a : 1 } )     list objects in foo where a == 1
        it                           result of the last line evaluated; use to further iterate如果想知道当前数据库支持哪些方法：

CODE:

> db.help();
DB methods:
        db.addUser(username, password) 添加数据库授权用户
        db.auth(username, password)                访问认证
        db.cloneDatabase(fromhost) 克隆数据库
        db.commandHelp(name) returns the help for the command
        db.copyDatabase(fromdb, todb, fromhost)  复制数据库
        db.createCollection(name, { size : ..., capped : ..., max : ... } ) 创建表
        db.currentOp() displays the current operation in the db
        db.dropDatabase()        删除当前数据库
        db.eval_r(func, args) run code server-side
        db.getCollection(cname) same as db['cname'] or db.cname
        db.getCollectionNames()        获取当前数据库的表名
        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 nonmaster member of a replica pair
        db.getName()
        db.getPrevError()
        db.getProfilingLevel()
        db.getReplicationInfo()
        db.getSisterDB(name) get the db at the same server as this onew
        db.killOp() kills the current operation in the db
        db.printCollectionStats()   打印各表的状态信息
        db.printReplicationInfo()        打印主数据库的复制状态信息
        db.printSlaveReplicationInfo()        打印从数据库的复制状态信息
        db.printShardingStatus()                打印分片状态信息
        db.removeUser(username) 删除数据库用户
        db.repairDatabase() 修复数据库
        db.resetError()
        db.runCommand(cmdObj) run a database command.  if cmdObj is a string, turns it into { cmdObj : 1 }
        db.setProfilingLevel(level) 0=off 1=slow 2=all
        db.shutdownServer()
        db.version() current version of the server如果想知道当前数据库下的表或者表collection支持哪些方法，可以使用一下命令如：

CODE:

> db.user.help();  user为表名
DBCollection help
        db.foo.count()                统计表的行数
        db.foo.dataSize()        统计表数据的大小
        db.foo.distinct( key ) - eg. db.foo.distinct( 'x' )                按照给定的条件除重
        db.foo.drop() drop the collection 删除表
        db.foo.dropIndex(name)  删除指定索引
        db.foo.dropIndexes() 删除所有索引
        db.foo.ensureIndex(keypattern,options) - options should be an object with these possible fields: name, unique, dropDups  增加索引
        db.foo.find( [query] , [fields]) - first parameter is an optional query filter. second parameter is optional set of fields to return. 根据条件查找数据
                                           e.g. db.foo.find( { x : 77 } , { name : 1 , x : 1 } )
        db.foo.find(...).count()
        db.foo.find(...).limit(n) 根据条件查找数据并返回指定记录数
        db.foo.find(...).skip(n)
        db.foo.find(...).sort(...) 查找排序
        db.foo.findOne([query]) 根据条件查询只查询一条数据
        db.foo.getDB() get DB object associated with collection  返回表所属的库
        db.foo.getIndexes() 显示表的所有索引
        db.foo.group( { key : ..., initial: ..., reduce : ...[, cond: ...] } ) 根据条件分组
        db.foo.mapReduce( mapFunction , reduceFunction , <optional params> )
        db.foo.remove(query) 根据条件删除数据
        db.foo.renameCollection( newName ) renames the collection  重命名表
        db.foo.save(obj) 保存数据
        db.foo.stats()  查看表的状态
        db.foo.storageSize() - includes free space allocated to this collection 查询分配到表空间大小
        db.foo.totalIndexSize() - size in bytes of all the indexes 查询所有索引的大小
        db.foo.totalSize() - storage allocated for all data and indexes 查询表的总大小
        db.foo.update(query, object[, upsert_bool]) 根据条件更新数据
        db.foo.validate() - SLOW 验证表的详细信息
        db.foo.getShardVersion() - only for use with shardingMongodb的备份工具mongodump

如果想备份数据库test 如：

CODE:

[falcon@www.fwphp.cn  ~/mongodb/bin]$ ./mongodump --help
options:
  --help                   produce help message
  -h [ --host ] arg        mongo host to connect to
  -d [ --db ] arg          database to use
  -c [ --collection ] arg  collection to use (some commands)
  -u [ --username ] arg    username
  -p [ --password ] arg    password
  --dbpath arg             directly access mongod data files in this path,
                           instead of connecting to a mongod instance
  -v [ --verbose ]         be more verbose (include multiple times for more
                           verbosity e.g. -vvvvv)
  -o [ --out ] arg (=dump) output directory
[falcon@www.fwphp.cn  ~/mongodb/bin]$ [color=Blue]./mongodump -d test -o test/[/color]
connected to: 127.0.0.1
DATABASE: test         to         test/test
        test.user to test/test/user.bson
                 100000 objects
        test.system.indexes to test/test/system.indexes.bson
                 1 objects
[falcon@www.fwphp.cn  ~/mongodb/bin]$ ls
2     mongo   mongodump    mongofiles   mongorestore  mongosniff
dump  mongod  mongoexport  mongoimport  mongos     testMongoDB的数据恢复工具mongorestore

查看test库中的表

CODE:

> show collections
system.indexes
User删除user表

CODE:

> db.user.drop();
True

> show collections
System.indexes现在利用mongorestore表恢复刚才利用mongodump备份的数据

CODE:

[falcon@www.fwphp.cn  ~/mongodb/bin]$ ./mongorestore --help
usage: ./mongorestore [options] [directory or filename to restore from]
options:
  --help                  produce help message
  -h [ --host ] arg       mongo host to connect to
  -d [ --db ] arg         database to use
  -c [ --collection ] arg collection to use (some commands)
  -u [ --username ] arg   username
  -p [ --password ] arg   password
  --dbpath arg            directly access mongod data files in this path,
                          instead of connecting to a mongod instance
  -v [ --verbose ]        be more verbose (include multiple times for more
                          verbosity e.g. -vvvvv)

[falcon@www.fwphp.cn  ~/mongodb/bin]$ ./mongorestore -d test -c user test/test/user.bson
connected to: 127.0.0.1
test/test/user.bson
         going into namespace [test.user]

         100000 objectsUser表中的10w条记录已经恢复

CODE:

> show collections
system.indexes
user
> db.user.find();
{ "_id" : ObjectId("4b9c8db08ead0e3347000000"), "uid" : 1, "username" : "Falcon.C-1" }
{ "_id" : ObjectId("4b9c8db08ead0e3347010000"), "uid" : 2, "username" : "Falcon.C-2" }
{ "_id" : ObjectId("4b9c8db08ead0e3347020000"), "uid" : 3, "username" : "Falcon.C-3" }
{ "_id" : ObjectId("4b9c8db08ead0e3347030000"), "uid" : 4, "username" : "Falcon.C-4" }
{ "_id" : ObjectId("4b9c8db08ead0e3347040000"), "uid" : 5, "username" : "Falcon.C-5" }
.................
has moremongodb还提供了HTTP查看运行状态及restfull的接口
默认的访问端口是28017

mdb_001.jpg

mongodb www.fwphp.cn-27017_1268719188106.png

rest的访问接口

mdb_002.jpg

参考地址：http://www.mongodb.org/display/DOCS/Http+Interface